As the other surgeons have mentioned, in order for a breast reduction to be "medically necessary," it must meet certain criteria. For the amount that is required by your height and weight, you are looking at somewhere between 900-950 gms per breast in order to meet at the 22nd percentile, which is what most insurance companies require. 1800gms might be your individualy carrier's criteria. This is could also be both breasts, which is fairly close. I would contact your insurance carrier's representative to discuss what your plan requires.
In addition most insurance companies will require more documentation and reasoning as to why it is medically necessary to reduce the size of your breasts than just a size issue. You should discuss this further with a board certified plastic surgeon to understand what your insurance company requires.