[Tiva]

You are worried about the wrong things. A breast reduction is a good thing if you don't feel comfortable I know it will help your back pain and probably your knee pain. If the people you currently hang out with don't like you after wards they don't care about your well being and aren't who you should be around.
I have had two friends and several family members have a breast reduction and there are a few risks, like having it before children because they would get larger again. Also your nipples may have to be moved depending on how much smaller they will be, there is a chance they won't retake enough to breast feed if you have a child, it is a known risk and why most women either choose not to have children or have it after they are done having children and breast feeding.
You won't be able to wear a bra for a while, i believe 2 weeks or so, until the swelling goes down at least. And depending on the size of the reduction you may have bandages to change for a while (2 weeks plus) also their may be scar tissue if you don't heal properly, but I still haven't seen anyone have it in my circle.
Also if you can ever afford a tight lacing corset (they run at least 100 buck) it will help hold up your breasts and make your back feel better temporarily.

In my opinion if it will help you feel better both about yourself and physically you should go for it at one point. If you want to have children and breast feed I would suggest you wait until after you have kids.