I don't think your boyfriend has any problem at all with your chest.
Breasts are either perky or big. Never both. Unless they're fake. So don't worry about how you look or how your breasts are hanging. They are exactly what they should be and are placed exactly where they ought to be. And I'm sure your boyfriend feels very luck to have occasional access to them.
Don't focus on other women's equipment. Just focus on your own and be thankful for what you've got. I promise that your boyfriend is thankful as well.