Depending on your financial situation, meaning that if you are on medicaid or medicare you may be able to have this paid for by the system.
I am sure that a doctor can and would be more than willing to refer you to an otrhopedic surgeon and then have him evaluate your back pain. After that, he may say you have legitamate spine problems that need a spine doc to fix before they give you a referal to a plastic surgeon to make the necessay reduction in breast size.
If by some chance you are greater than 27% body fat, they may also put you on a weight reduction plan to see if your breasts will shrink to a more equitable size. This does not mean that you will not be a cadidate for breast reduction but you have to keep in mind that breast reduction is an extreemly painful and dangerous procedure. Unlike breast augmentation, with the reduction they are removing a large amount of skin, and muscle tissue and so healing and recovery is tedious and painful.
Good luck,
-brian