Insecure and Self Conscious During Sex

I really need advice. I’m not fat fat, but I’m not skinny either. I’ve been with my boyfriend for a reeeeeally long time. Not once has he mentioned or pressured me into sex, though i want to and i know he does as well. But the problem is I’m very self conscious, so we never even talk about it. My mind thinks that if he sees me naked he’ll leave, though i know he would never do that. And he might be grossed out by my fat or rolls or whatever. I’m not sure how to get rid of these thoughts. And it’s not even like I’m insecure 24/7. Just when it comes to him. But the thing is i have absolutely no reason to, he’s never made me feel ashamed. :( I’m not sure what to do.