I'm new to this site and I want to thank anybody ahead of time if they choose to take the time to read my thread. I'll try and be brief and spare the unnecessary details:

I'm 30 years old, live with my best friends in a lovely home and have a full time job doing ok for myself, albeit my job is very stressful. I began dating my current girlfriend early September, when it became official. Her and I have been aware of each other for a couple years from coincidental situations and when we began talking this passing summer (it's beginning is a the best "romantic" story I've ever got to tell, BTW) we admitted to have always be drawn to each other but lack of self esteem on both our ends prevented us from approaching one another. Either way we basically fell very fast for each other and I can honestly say I've never felt this much for a girl despite all my past relationships. She claims to feel the same for me and considers me the first person she actually can say she is in love with.

My issue, flat out, is that I keep telling myself this isn't going to last. She has given me very few reasons to think of her as someone who doesn't want me but still I keep insisting, also vocally to her, that I feel she is going to leave me one day. I blame it on all my past relationships and the insecurities they all left me with definitely, but I can't control the feelings no matter how much she reassures me. She always knows when something is bothering me, whether face to face or text and lets me vent to her and listens, something nobody has done for me. She constantly tells me she is in love with me and can't guarantee we're going to be together forever because that's unrealistic, but I am who makes her feel complete and she's never felt that before, in many many more words.

I'll find things to nitpick and question her about just because it may of happened in a past relationship that ended up being something that hurt me. She knows how I am and she still remains patient, openly explains anything I could possibly dissect and make a negative assumption for and tries to help calm me down. But then it'll happen the next day, and eventually it becomes me repeating the same things to her and her telling me the same story again. She has the patience of a saint and I feel terrible I'm putting her through this. She doesn't admit to being pushed away but she is starting to think I don't want this as much as she does now. She's starting to think I'm doubting her despite her saying she made her choice and knows what she signed up for, and I'm tired of making her deal with it. I want to be secure with myself enough to feel secure with her. When we are together we rarely argue and if we do it's settled maturely, something I'm also not used to. I just want us to be happy and comfortable like we were.

Has anybody had ways to help themselves in this situation? I worry that me thinking our relationship has a limited time isn't anxiety but a gut feeling and I can't tell the difference. I want to go back to how I felt before all this since it's almost an every day feeling. I guess the closer I get to her, the more I feel like I have a lot to lose. I apologize if this was a burden to read but greatly appreciate any advice.