Will my Boobs Grow Back?

It's great that you lost so much weight, and this will lead to a healthier overall situation for you- congratulations.  Breasts getting smaller after weight loss is a very common situation.  In older women, this is usually a new "reset" point after weight loss because they don't have fluctuations in hormone levels and growth spurts that you will expect at your young age.  It is very likely that your breasts will continue to grow over the next few years, and despite your recent weight loss, your breasts may very well "grow back" as you progress through your teens.  Be patient and I would definitely NOT recommend even considering breast augmentation surgery for a few years until you are certain your growth has stopped.

First, congratulations on your weight loss.  It is very common for women to lose volume in their breasts with significant weight loss.  As far as breasts "growing back", you are still quite young and your breasts have not finally matured yet.  You may get more volume over time.  There are also things that will influence your breasts, (having babies, breast feeding, weight gain/loss).  Wait and see what happens.  If you have questions seek out a board certified plastic surgeon and ask him/her the questions that you have.

At 15, you have not yet attained your full adult dimensions.  Your breasts may still change.  Also, breast tissue changes with weight gain/loss, pregnancies, periods, etc.  No one can predict how they will look down the road.  You will just have to cross that bridge when you get to it.