Asexual?

I have never really felt turned on, I don't find people attractive and I don't like or want sex. I have been to doctors to see if there's anything wrong with me and they say I'm fine. I'm 26 and I feel so outside. Everybody's life seem to revolve around sex and they all enjoy it and here I am feeling pretty disgusted by it. I have been in a few relationships and I am in one now too and I really love my man, but I don't like sex or anything sexual at all and it's really hard for me. I have been completely open with my partner, told him I'd understand if he would break up with me, because he's got a high sex drive, but he wants to be with me. I don't know what to do anymore. I'm really scared of going to a sex therapist with my partner because I'm scared they will say I have to force myself to do stuff with him. I can tell he's not feeling very well when he doesn't get to have sex or any other form of sexual pleasure. I have even suggested he goes to someone else to get what he needs and then he gets mad. I don't know what's wrong with me. I want to love it but I don't. I have never experienced any sexual assault or so, so it's not something traumatic that causes it. I'm not depressed or anything either. Any advise?