Dogs don't speak human, but they are very good at sensing peoples emotions and they do speak dog. You are suppose to be the smarter one of you two, so it's way easier for you to learn how to speak dog, than it is for her ever learn how to speak human. Especially if she is a breeding dog and has lived with several other dogs before, she probably is the master of speaking dog.
She has probably told you with ten different clues, she doesn't want to be around you, before she actually has to get up and escape. Your job is to learn, when she is trying to tell you she doesn't feel comfortable, and respect it. Your job is also tell her, using HER language, you don't mean anything harmful.
You can also google for calming signals, or buy a book called Calming signals by Turid Rugaas. They are little things dogs do, when they are either trying to tell, they are not comfortable, and they don't want to get in to any trouble with you. Also when another dog is stressed out, they can use those same calming signals to assure the scared one, they don't want anything harmful either, so it's all good. Basic meaning of a calming signal, is just the one it's name tells you: to calm someone down. They use them to calm themselves down, and to calm others who feel aggressive or scared. Same signals calm down from any overwhelming feeling.
First you need to know what are not polite things to do in doggies world.
1. Staring. Never stare a dog. People look each other in the eyes when they speak, and it's a positive thing to many of us, but in dogs language, they fixate their eyes straight into something, when they are going to hunt that thing down. You can look at dog in the eyes, but only for a couple of seconds, then look away, then watch again. But now that you are just starting with her, it could be good not to look at straight at her at all. Remember this all the time. (When you are dealing with the dog that is trustful, they may be used to people staring and not meaning anything bad, but it's still not polite.)
2. Walking straight to them. It's not polite in doggies world to go straight to someone. Some dogs do that, but they either know the one they are approaching or they ARE not polite. Lets pretend she is sitting on your girlfriends lap on the couch, and you want to go sit next to them. Don't walk straight there, but go around. So if the shortest way would be go straight line, do a half circle instead. In human body language it's polite to go straight to someone and shake their hand with an eye contact and smile. In doggy language, that would be a threat in four different ways.
3. Bending over above. If she is on floor, and you need to go to her, like for example put her on leash for going out, don't bend over her. Don't ever do it, she will just back away. Go side by side with her, and bend forwards, then you are not above her. In everything, it's better to do things side by side, than face to face. If she is too scared of not to face you, then it will be her face but your side.
4. Touching her without warning, touching her from above. If she is scared of you, she doesn't want you to pet her. Respect that. Also dogs don't like to be tapped to the head, just like people doesn't like it either.
5. Growling, barking out loud, showing teeth. In human language smiling is polite and nice, but dogs won't probably understand your smile as a nice gesture. They think you are showing your teeth, and threatening them. Many dogs learn people do weird things, but aren't scary anyway, but maybe she hasn't learn that. Also loud speaking voice and speaking on low tone can sound threatening to them.
6. Hugging. Dogs don't like to be hugged. You can google pics of dogs being hugged, and see that almost all of them are looking the other way which means they are using calming signal to make hugging stop. They can get used to it, but in dogs language, placing their paw on someones back, or paws around another dog, it's a threat. It's either a real threat or it's pretend one in a play, but it's not how they show affection. I've never seen a dog in my life who likes hugging. They learn to cope with it, but they don't understand why they are suddenly threaten, and they feel uncomfortable.
If she is scared of your voice, concentrate on that. Talk a lot to her, but don't look at her. She doesn't need pampering or pity, she needs encouragement and support. Talk with happy, friendly tone all the time. Talk about anything, she doesn't care what your words are, she understands the mood you are on. If you are stressed, concentrate even harder. They can hear the difference, when the voice if flowing out, or if it's tense and also when you're tense, your pitch tends to go higher. She will be OK with your voice, when you have talked to her few days, and it hasn't meant anything bad to her.
Then about those calming signals. Do not stare at her, but you can see with the corner of your eye well enough, if she is doing any of these for example:
-turning her head away from you
-looking the other way, even for a second
-squeezing her eyes
-turning her side or back at you (if she's really scared, she may not dare to)
-licking her nose or lips
-freezing
-moving very slowly
-yawning
-moving around in circles
-sniffing the ground, or something near her
-lifting her front paw
-sitting down, then (maybe) laying down
When she is doing any of the things above when you are getting closer to her, it means she is sending you a calming signal. She is stressed. So don't go any further, but you can also answer with another calming signal, like turning your head away the way it doesn't leave her quessing.
I would start with talking. Do that, until she no longer reacts to it negatively. Move around, and let her see, you are not gonna go at her, until she relaxes, and doesn't care you are moving around anymore. Talk while you move, with friendly, happy voice. This may take days.
When she is OK with you moving around, go somewhere near her. You see it from her calming signals when she starts to feel unsure, stop there. Sit down, sideways with head turned away, or backwards to her. Continue talking there for a while, and then go away. Do this many times, and she will learn, you can come to her and sit with her, and it's still not dangerous. If she ever needs to leave away, you went too close or she wasn't ready to do the next step. Basic idea is to start to get closer and closer everyday, but always try to stop before she needs to show any calming signals, then she is scared already.
Even when these are not things you would do at home alone, act normally, like they would be. Don't make big issue about anything. When you can not follow the instructions let her be and go away. Don't let your child parts, or parts that are not interested about her, ruin her trust.
If she dares to come near you to sniff, do what you were doing when she came. Don't pay any extra attention on her because of that. She doesn't want your attention, she just wants to know how you smell like, to her it's knowing who you are. She can come back again and again, when she knows nothing different will happen because of it. Don't make anything she does a big issue. Inside you can feel happy she came, but outside stay as calm you were before.
When doing exercises like going next to her, always end them by just leaving her alone. She learns to trust, that you are very predictable, if you came to just talk, that's all you are going to do. At first, now that she is scared of you, it's her reward to be left alone. But they are social beings, so they don't want to be left alone for good.
Don't ever surprise her with anything she didn't see coming. When she's ok with you talking, walking, and sitting next to her closer and closer, until you actually do touch each other, it's ok to touch with your hands too. But show your hand to her, palm side up, and move it closer to her, until you touch her with your hand. If she gives you calming signals, stop there and don't touch that time. Then say you are sorry by showing her a calming signal too.
Personally, I use fake yawning a lot. It's very clear, visible and audible signal and they seem to react to that one with more interest than to some smaller clues, like licking lips. I also fake scratch myself with my hand like a dog would with their back paw, and it gets them interested, or calmed if they were getting worried.
https://www.youtube.com/watch?v=WcZKBoGn6uc Here's a short video about the same thing. If she is your first dog, and she is traumatized, it's more than important to learn to understand what she's trying to communicate with you. Personally I would never ever give a dog like that to people with no experience how to train a trauma free dog first.
Be aware, if her tail is up or down, if her ears are up or down, etc. There is a lot scientific proven knowledge about dogs learning processes and dogs behavioral. And there are tons of people with self-learned skills trying to advice you also, sometimes with true understanding, but sometimes doing more bad than good. Don't listen to just anyone. In my country it's very clear difference between different trainers, some are legalized professionals, and their methods are safe and based on real studies. There are also all kind of do-it-yourself -trainers, some good and some dangerous. I don't know if you have any list of actual professionals in your country, but if you do, it's not a bad idea to call one. It's impossible to give sensible advice to a case on-line about something I have never seen, and to a owner who has no ability to read the dog well yet, so it's all guessing.
I hope this is all something you have been aware of before hand, but if it's not, it's time to do some serious research now.
Good luck with her! Be gentle and always remember the most important thing, they will always have to have a right to leave away from the situation they feel is too stressful. Then it's people job to do it again better, without forcing.