I'm too fat for my boyfriend?

Megan

My boyfriend and I have an amazing relationship,we are totally in love and were basically on cloud nine. I was a size 6 when we met, and very very skinny and dainty. Fast forward 7 years I'm nearly a size 20. He says he loves me as I am but I've noticed on his Instagram he follows lots of models and nude profiles, I'm not bothered as I watch porn sometimes myself but I followed some of the profiles he follows and the all have one thing in common... pretty skinny blonde...which I once was. I know I'm reading to much into it but it makes me feel down. We used to have sex 4/5 times a week when I was a size 14 but now I'm bigger he says "it's not all about sex you know" I don't think he's cheating but it puts my confidence down a lot. I'm trying to lose weight for myself not just for him but I constantly feel like I'm competing with my old self and thinking that he loved and found her more sexy😔 advice?