You will understand this question after I introduce it to you:
In the early stage of development, you should wear a small vest for protection, and it should not be too tight, nor should you wear a bra, otherwise it will hinder the normal development of the chest.
When you grow up, you should wear a bra. -Otherwise, you can't rely on your breasts without wearing them, which will easily lead to sagging and outward expansion. ~ ~ For example, your swing during exercise will hurt elastic fiber tissue. ...
Are you still young? If the chest has obviously started to bulge, you should wear a vest now. You'd better take it off when you sleep. Of course, if there is no bump, you don't have to wear it.