How to go down a bra size?

Gracie

I’m 20 years old and currently wear a DD. I wore a D in high school and was happy with it, but college stress and dining halls made me put on some weight. Most people say I’m crazy to complain about this issue but it’s frustrating when I can’t shop for a new bathing suit top or shirt without my boobs hanging out or being constricted. I would love to get back down to a D or even a C! Any exercises or tips on how to reduce breast fat?