In a long term loving relationship but not sure if I am gay

I'm 22 and have been in a straight relationship for just over two years now. I am pretty sure I am bisexual but I think there is a chance I may also be gay and it's a part of myself I've never explored.

I've thought I might be a lesbian since I was 13 after crushes on friends and a lot of interest in the female body. Since then I've been back and forth on what sexuality I think I am, but apart from kissing a lot of girls at parties during my teenage years I've never really explored that side of myself. I've now been in a relationship with a great guy for 2 years. I think he is amazing, he makes me smile and laugh, and he's the best person I know. We have good sex but I never feel fully comfortable and have also never had an orgasm.

The longer we have gone out the more intense my worries that I may be gay have got, as I can see myself marrying him in some senses but then on the other hand I think I might be gay and I won't know until i explore that side of myself, and I think I will resent him and always question my sexuality unless I get to, but if I break up with him and I'm not, I may have lost the person who really is the man of my dreams.

 

Thanks for your answers. I have tried watched lesbian porn and I definitely find that it's a turn on for me, and I enjoy fantasizing about women, but I have still not been able to orgasm. And I think the reason that I dont feel completely comfortable with him is because I am not completely sexually comfortable with myself, but I wonder sometimes whether that might be different with a woman? I guess I just dont know whether it's something I should talk to him about as well and voice the confusions that I'm having, or if that's just a terrible idea?