Why do I stay with him :/ ?

My fiancee was what I thought I have always waned but we have nothing in common , he wants alot of things I don't , he drives me totally insane !!!!!!!! He told me I should lose weight and I'm chunky probably 155-160 and I like the way I am. One night he told me that he's not sure I'm what he wants but he thinks he needs me to mature... Does that mean he is using me ? I really need help somehow I love him but I want to let go or figure out what to do. ( were 9 1/2 months into this relationship)