Getting a breast reduction?

I'm 19 years old and I've been a D cup since middle school. I'm not particularly thin (~170lbs and 5'5 --I've lost weight before and the boobs stayed the same size. Honestly, I think they may have gotten bigger since last year), but I've been experiencing back pain for the past few years and my mom mentioned the other day that it might have something to do with my boob size. Even when I'm sitting down, it feels natural to sort of slump forward because my boobs feel like they're pulling me down and my back arches and my shoulders roll forward. I've been trying to practice good posture for years and I sit straight when I consciously think about it, but even when I'm just walking along I feel like I'm being pulled forward.

I had a relative get breast reduction surgery a few weeks ago and asked about it and she told me that she feels so much better with having gone to a B/C cup. I told her about my back and shoulders and she says she had that issue to and her insurance was able to cover everything because it was medically necessary. I think I was a C cup for a year or so in the fifth or sixth grade but then ballooned up to a D/DD cup size. My bras (no matter what kind I buy) dig grooves into my shoulders that hurt, leave scarring and will actually get these weird bumps on them that swell up and hurt like hell. Not to mention the pain in the *** it is to do anything that involves jumping or running without wearing two bras. *embarrassing*

And superficially, it would be super nice to have an easier time finding shirts that fit, but I can stretch the shirts; my shoulders and back are what's bothering me. I won't be able to see my pediatrician until around Thanksgiving or Christmas break because I'm away at school. Should I mention this to him?

(I'm a college student, but my bookbag is never heavy because of the way I schedule out my classes to avoid bringing more than one of 500+ page, hard cover, science textbooks.)