I think maybe you just are not ready for a sexual relationship. Some people just do not like sex. Some people can take it or leave it. Some people enjoy it right from the start, some people like it only with committed partners, some people like it only without the love relationship attached. Just because you have a boyfriend you love does not mean you are supposed to fall into a sexual relationship and love everything about it from the beginning.
For me, I have to be in a committed relationship, I have to trust him completely. The first real relationships people have can be overwhelming, and it may simply be that you are not ready for it. Just because you lost your virginity does not mean you are supposed to now have lots of sex and be great at it and love it. Great sex does take practice, but you have to be emotionally ready for it. If right now you would like to slow things back down with your boyfriend, talk to him about it. Ask him if he is willing to take it back to before you had sex for a few months. See if you feel better during that time. He may not agree though. For some people sex is a very important part of building the couple bond. He may not feel as close to you without the sex. I am NOT saying you should give him sex to keep him. I'm saying that if you are not ready, or if you are not the type of person who bonds through sex the way he does, maybe the two of you are not compatible right now, just as you wouldnt be compatible if one of you was a vegetarian and a peta member and the other was an avid hunter. You cant keep giving him sex that you dont want, because it wont be good sex and while giving in might keep him for now, it wont keep him down the road when it isnt mutually exciting sex.
The other thing you can do is try to figure out for yourself what you do like/dislike about it. Are there things he does that feel good, while other things dont? He cant get better or learn to please you if you dont know what you want yourself. So think about what you want, and either decided to step back from sex for a bit or decide to try and make sex better for you, or do a combination of both!