Here you go. Take what you will from it.
(The original is on the left side. My edit is on the right side)
I think your sprite overall is very nice and cute.
I'm sure someone else could do a much better job with the hair than what I've done with it.
As for your question on boobs, you have to first make a solid decision on the size and shape. Once you've got that down, try to transfer what you want onto the pixel-drawing board. I gave your sprite average ones.
The trick to making breasts look natural is to think of them as extensions of the chest rather than two objects stuck on the chest.