In the bedroom

I feel like I'm bad at sex. I never get on top because I'm self conscious aka I'm fat (180 lbs. at height 5'6") and my boyfriend is average (175 lbs. at 6'4"). I just don't want us to be having sex and him see my fat rolls...... So he's always on top and we never really do any other positions. He is always satisfied aka he always cums but I've never had an orgasm while having sex. We love each other and have been dating 10 months (have been having sex for 6 months). Does anyone have any advice?