While it's possible- - the odds are that you might have some more breast growth still ahead of you. Ideally, it would be better to wait until you're done developing. But if they are already very large, and you are getting teased a lot, talk it over with your parents, and have your mom go with you to see a plastic surgeon. The surgery will make your breasts smaller, lighter and perkier - but there will be scars.
Possibly. A liposuction reduction can be used to reduce your size without large surgical scars. If your over weight, weight reduction may reduce the I've of the bust. I would wait till you have stopped growing before you consider conventional breat reduction surgery. I would also review the scarring that results after surgery so you are prepared for it after your surgery.
See a plastic surgeo. Some plastic surgeons will perform a breast reduction at that age. Some will not. You just have to discuss it with a plastic surgeon.