Low sex drive

My fiance and i love each other oh so much. But for some reason i cant have sex more then 1-2 times a week. And it really gets in the way of our relationship. Im only 24 and i have never been big on having sex. Never cared. He's 30 and loves sex multiple times a day. Because i never ask for sex and says no everytime he ask he thinks im not attracted to him, but i am. I just dont know what's wrong with my body. I never really put to much thought into it because iv neen this way my whole life. ANY ADVICE?