How young is too young to get a breast reduction?

Molly

I’m 16, and 5’8”. I currently have size 34DD-36DDD (depends on the store/brand of bra). I a have a very slight frame (im 117 pounds). I suffer from constant sternum, back, and neck pain and am seriously considering a breast reduction. Should I wait until I’m 18?

Update: I have insurance and parental support.