I'm unsure

my girlfriend and i have been together for almost two years. im diagnosed with major depression, mild anxiety, and PTSD. my girlfriend has major depression, major anxiety, and (undiagnosed, since shes too young to be. therapists/doctors do all agree she has it though) BPD. our relationship is really nice, considering. i do love her. i guess to put it in perspective, im a girl that's a young teen, and my girlfriend is also a young teen . so we're pretty young.

the friendship started back in 8th grade with us just being friends. we had only 2 and a quarter classes (a half because she was only in one of the four quarters of a class) together. we became best friends and yadayadayada. eventually, after both of us knew we had crushes on each other, we started dating.

the first couple of months were okay. you could say perfect for a first relationship. it was sweet and cute. a lot of cringe when i look back at the messages. but cute. it started when i was 13 i believe, so it makes sense. but you know, young love. (oh, i forgot to mention. since we got together on the last day of school, it was summer. sadly, her dad hated me then, so we didn't get to see each other for the first few months of our relationship.)

now that we're two years into the relationship, we've known each other way longer than we knew when we started dating. i now live in a different state, which is really difficult for my clingy personality. im in high school, too, which makes everything worse. either way, we're making it work. we talk almost everyday, with the exception of people cant be in communication all the time (so we take some breaks).

our problem consists with her BPD. i love her. i dont want to ever leave her, especially not over her mental illness. but in some cases, im scared. she switches between phases of herself, and sometimes im terrified. i love her regardless, even whilst in this shift, but it is quite honestly hard to 'not shut down completely.

when shes in this "shift" (thats what im just calling it right now, it does have a name but, thats personal) she doesnt usually say "i love you" back, nor anything of the sorts. its worse feeling when she says "love u". it used to just be a shorter way to say i love you, but it means a lot more here. you know its on purpose, because two seconds before, or later, she would say a full "you". it just happens to be one way i know shes upset, and its been proven.

im really just wondering if anyone knows what i should do?

i dont want to break it off, no desire either. but i dont know if its whats best? i could even have stockholm syndrome at this point, and not know if it is abusive. i dont think it is. just a little difficult. i love her, so i really am confused.


brye

i was diagnosed with BPD when i was 18 and it definitely affected my relationships. i think i understand now what i put people through back then when i would shift moods, snap at them, withdraw affection, etc.
my suggestion is two-fold: one is to read up on the disorder. understanding it will help you put her behavior into a greater context and enable you to take things less personally. that said, the other part is to focus on taking care of yourself. figure out some boundaries and stick to them. if she's being mean or cold, let her know that you are affected by it and that you need to take a break. ensure that she knows this isn't you LEAVING, it's just to recharge yourself. focus on positives. tell her the things that she does that are good - i don't mean flattering her, but communicating which behaviors are constructive and healthy for you two as a couple.
when you're borderline, it's very hard to understand that other people DON'T feel the crazy mood swings you do, and it's hard to believe that people still care about you when they keep their distance. but it's also important that they are taking care of themselves, otherwise you can feel like you're controlling and abusing them, and that leads to a cycle of self-hate, resentment, and more bad behavior.
TL;DR is be strong, take care of yourself, and communicate clearly about how you feel.