Going off my husband?

I feel awful writing this, but I'm really worried I'm going off my husband. We had a miscarriage last year and we are having problems to conceive (I'm not ovulating) since so we've been having a lot of sex! But I'm finding lately I can't feel turned on by him, I'm not worried about sex apart from to conceive and I'm struggling to fancy him. I feel like an awful person!! He's about 20 stone and I'm 12 stone so every time we do it I feel his weight on top of me sort of thing which doesn't help. Am I a terrible person??