Have pcos. is it possible for breasts to finally develop & catch up w/ some kind of treatment?

Genetics...: Your breast size is mostly determined by a 'roll of the gene dice'. I doubt your pcos has anything to do with it. Naturally your breasts should enlarge with pregnancy and lactation. Keep in mind the primary function of the female breast is lactation for infants. And size doesn't influence that function. If you think you must change you can always consider implants.

PCOS: Unfortunately, pcos is a complex harmonal problem leading to multiple metabolic problems. Wieght loss is the scientifically proven treatment to help regulate the harmones. I would suggest you to consult an endocrinologist. Good luck !