I want to be a better boyfriend

I (24M) have been with an amazing woman (23F) for the last year. I’m at a really low point in life and don’t want to drag her down with me. I have $1 in my only checkings account. I have a dead end job which I struggle to meet ends with. She knows all this yet has never left my side. Saying all this out loud, it’s clear as day there’s not much better I could ask for. The problem is me. I have severe trust issues, and although I’ve never spoken about my problems with others (therapy and the sorts) I’ve concluded that it stems from trauma I felt from being harshly cheated on from my ex girlfriend/my first love. I had spent a lot of time after that relationship ended single and “working on myself” but as soon as I entered this relationship, literal years later, all the issues I thought I had pushed aside just consistently come out. I always believe in the back of my mind that she’s cheating on me in some way shape or form, even when I have no reason to think so. Something as simple as a guy showing up in her life even as a friend bothers me and I get controlling to the point where she feels obligated to not talk to them anymore. I cause a lot of problems in the relationship and I try my best to fix my mistakes but it’s a long cycle of failures and coming up short. I feel like in a sense I’ve lost a part of her that hasn’t ever and will never come back due to all the things my issues put her through. Even though I give her all the reasons to leave, she still stays with me. I need help and genuine guidance on how to save myself and save my relationship. I know the answer is something along the lines of loving myself or fixing all the problems I have but I don’t know how to, so please if anyone took the time out of their day/night to read this, id appreciate anything. She means absolutely everything to me.