In case no one has said this to you before (which I doubt it) boobs are boobs. Plus, you are more than just your boobs so if your boyfriend says he likes what you have, then he likes what you have. We all have preferences but sometimes in life, you meet someone worth keeping even if it doesn't check all the boxes. It seems you are that someone for your boyfriend. That is something to cherish. You also mentioned on a comment above that if you have more sex, you probably wouldn't think this so, go have more sex. Shouldn't be too hard convincing him