I love my girlfriend but I might not be in love with her

I'm 24 and have been with my girlfriend for about a year and a half. From the start, our relationship has been plagued with issues out of our control - namely, the fact that my parents are completely unaccepting of our relationship or the fact that I'm gay. I came out to them shortly before I met my girlfriend, but I've known I was queer for years. They took it extremely poorly, and now, in an effort to get me to "turn straight," they actively try to sabotage my relationship by trying to convince me that my girlfriend is manipulative and immature and that our relationship is unhealthy.

In spite of this outside pressure, I think we've done pretty okay for ourselves. There were some very rough times and we even broke up briefly, mostly because she felt like she couldn't handle my family situation, but we stuck it out in the end. Overall, we're very supportive of each other in the bad times and in the good times, even though I struggle a lot with depression, especially lately. I love her a lot. She's sweet and wonderful and my ray of sunshine.

But I'm writing this post because I have these incessant doubts about our relationship - that maybe she's not the right person for me, that maybe there's someone better for me out there, that maybe I'm not really "in love" with her - and it's taking a huge toll on my mental health. This is my first relationship. I've never been with anyone else. I've always been a strategic person who has to pore over all possible options in a situation to make sure I'm making the best possible choice, and that side of me won't shut up. These doubts take on many forms. Like I worry that I'm not really that attracted to my girlfriend and that I only like to be intimate with her because she's a woman, not because she's her. And I worry that she and I are too different in important ways, like I'm ultra neat and she's messy. Basically, I worry that maybe we're not the best possible fit for each other, even though logically I know there's no way of determining the "best possible fit" between two people.

I'm utterly confused and distraught. I love my girlfriend and I think leaving her would break both of our hearts. We have so much fun together, we understand each other, and I think our personalities complement each other well. And I do love her and care for her so much. But I panic when I realize that the more time goes by, the worse it will be if we do break up. Maybe I'm over-analyzing things, but I don't know where to turn, and I feel like I need an outside opinion on this.

Thanks for reading.