He's making me even more insecure fml

Almost once every week my boyfriend will randomly stare or grab my boobs through my shirt and say "they're huge!" "They're getting bigger!" and act like he's amazed. But they're not huge. Only a B cup and aren't growing. It's like he's trying to make me feel good about myself but that makes me feel pathetic and humiliated. All his ex's had huge racks like double G cups and I know he watches porn with big breasted women so when he tells me I have "huge" boobs I just want to cry. Seriously he makes me more insecure and hate my size more than I already do and I want to smack him. I already told him to stop saying it and he won't. And during sex he doesn't take my bra or shirt off, ever.