No sex.

Me and my boyfriend have been together for going on 4 years and he has no sex drive!! He is 19 and I am 18 and I have the sex drive of an 18 year old boy while he has the sex drive of a old woman, and at times I feel as if there is something wrong with me! I've talked to him about it and he said that nothing was wrong with me, but he isn't ever in the mood! I don't want to push him but it's quite fusterating! Any tips?!