Hi there, I'm currently going through a bout of ROCD/anxiety and depression and know exactly how you feel. I love my boyfriend more than words can say but these thought still come ALL the time "do you really love him?" "is this the right thing for you?" "maybe you will be better alone?" etc.. they are intrusive and they leave me in such a terrible state because the thought of leaving my boyfriend pains me so much. From what you're saying with how you're feeling it sounds to me like you may have depression. Thinking you have no life and saying you don't want to live are signs of this. Maybe have a look into it and see if you agree? My depression is how my ROCD started.I am finding it hard to be happy with any aspect of my life but because my relationship is the most important thing to me I notice the lack of happiness more, that is what makes me have those doubts and once you let them in, they're there and don't seem to go away. You have gotten yourself into a very dark place but you can come out of that and you NO WAY have to leave your girlfriend. NO WAY AT ALL. You are relying on her for happiness right now and that isn't 100% her job. You have to make you happy. I know you are struggling with self love and things but that is honestly something you can work on. And because you don't feel love for yourself doesn't mean you don't love her, not at all, because all this is clear you do. Its just harder to feel the love you have inside of you when you don't love yourself, but it is there, trust me. You just need to have your own life as well as the life that you two share. Try and exercise and find a job, a hobby etc.. things to keep your mind occupied.
Basically what I'm trying to say is, you love her. There is no doubt about it when you look at it logically. But you do have anxiety and OCD and this is a completely normal way to feel trust me. Once you accept that that is what's wrong, when you feel the doubts and panic kicking in, you can tell yourself "this is just my anxiety talking, you love her" because that is the truth.
I hoped this has helped in some way, it truly is awful what you're going through.