When I was nursing my son, I was an H cup. I had always been big chested, but it was just painful- my breasts hung below my navel, even when full. I could not carry my son in a front-carrier and had trouble lifting groceries, etc. just because my boobs were in the way! I could not take the post-natal yoga mommy and baby class I had signed up for- you guessed it!- because my boobs were so in the way that I could not maintain the proper positions and hold my son on my chest!
I just bought every cheap bra or jog-bra I could find that I could manage to fit my chest in. And- once I was done nursing, a year later I had a breast reduction on my doctor's advice. The weight of my chest was pulling my whole backbone and shoulders out of alignment and I was building up calcium deposits between my shoulder blades- setting myself up for a 'hump' when I was old.
I have to say, for me, it was the best decision I EVER made. It was not very painful, my mom came and stayed with us for 2 weeks because I could not lift things, - and now I am a C cup. I lost weight, exercised and just felt 100% better and happier.
So I know you don't want to do this just now, but keep it in mind for later. Having a breast reduction truly changed my life :)