I feel pretty ugly compared to these models in the changing room.
What is your reason for feeling like a troll?
Because I feel that their boobs are much bigger than mine
I'm sorry you feel insignificant towards them all, but comparison is the worst thing to ever subject yourself to. There will always be someone better than you in some way, and you will never feel perfect if you keep comparing yourself. Be happy in your own unique skin.
How do I do this?
Do not worry about what the other models look like. Just make the most out of your body and feel content with that! Comparing yourself with others is just always going to leave you feeling lesser than someone else.