I don't really know how to phrase it, but I've been having doubts about my sexuality, and talking with sex-positive friends hasn't really helped.

I'm a bisexual man, and to be honest I don't find any kind of genitals appealing/arousing, it's just another body part to me. I've had partners/friends tell me that a picture of genitals sent by someone they're attracted to is enough to make them horny, but I've found that for me it has the opposite effect.
Also I find any kind of bodily fluid repulsive, which has been a problem when engaging sexually with others, though I haven't really told them because I don't want them to feel bad about a normal thing that I should like. I've never felt the need to have sex with someone I wasn't in love with/in a relationship with, but even then, I would be lying if I said I really enjoyed it that much. I mean, it's nice and all, but pretty boring overall, and now I don't know if I was only doing it to please my partner.
Anyway, I'm lost. What do you find appealing in sex, and in genitals? How come people want and enjoy having casual sex and I don't?