it can get better. You are so young, your body is still developing. Skin firmness and hormones are on your side given your young age.
Wanna give you hope but please do not expect miracles without a surgeon. Once they hang, it is normally too late. These advice are more for prevention of further rolling south and a bit for improvement.
1. Be careful about that yoyo weight between restricting and binging.
That takes its toll on legs, hips, breasts, belly etc. The other body parts however you can way easier reshape lean firm and nice through sport than breasts.
2. Wear the right kind of bras and do the right types of sport
Push-ups are no good. Sport helps a bit with the muscle undear the breast tissue.
Don't jump around like a Thomsons's gazelle.
3. Right nutrition and hydrating from in and out
Use creams, body lotions etc for your skin, drink enough water. Diversify your things on the plate.
4. Check hormones levels
In the rare case your breasts explode by a couple sizes within just a few months, then no cream and sport can save you from gravitation.
I answered something similar 3 months ago, more thoroughly, please have a look: