Struggling being comfortable in a relationship because of self esteem

Ok so I haven't done a ton of dating. And when I have in the past, it was while I thought I was straight, and it was just a few dates with guys that never became anything serious. Now that I'm coming to terms with being gay I'm starting to talk to women/actually able to potentially date women that I'm interested in. Recently I've been talking to this really amazing, beautiful girl and I like her a lot and I know she likes me a lot too because we basically are in that awkward stage of not dating/not "just friends." We both have feelings for each other.

So here's the problem: first of all, I don't hate myself for being gay at all--I'm past the self-hatred stage of it all--but for some reason I'm have so much difficulty being comfortable with viewing myself as in a relationship. I think it's a self esteem issue, because I feel like I am always wondering how/why this girl or any girl would ever be interested in me the way that I am in them. Yet, I really like this girl a lot and she likes me a lot too. But I guess, for lack of a better way to put it, it's hard for me to accept someone else's love because something feels off about myself. I love girls, want to be married someday etc... so it's definitely not an asexual thing. I know for a fact it's just me being uncomfortable or something like that. Has anyone had this and do you know what I can do to help? :/