That"s a myth. Breasts become saggy/deflated as a result of becoming pregnant, not breast-feeding. When the breasts become engorged as a result of prolonged hormones (i.e. the body knows the woman is pregnant and will need to provide milk), the extra weight can cause sagging and (often) a downwards angle of the nipples. After a time following birth, when breastfeeding is no longer biologically imperative, the breasts maintain their general shape while shrinking in size.
I don"t think you"ll see that with a shooting-star on NBC.