Your cup size will go up in letters as your band size goes down in inches. So don't let that discourage you! As long as that band keeps going down, then everything is good!
Sadly, for us big chested ladies, losing enough fat from our breasts to make us comfortable will take a LONG time. Or, your genetics have decided it won't happen. After my reduction, probably a year later, my genetics kicked in and I grew a cup size but stayed the same band size. I was not impressed but at least they haven't grown anymore!
Your surgeon may not let you do the surgery until you have lost the weight... if you do it first and then loose a lot of weight it can screw up your results. But if insurance will cover it, then I would whole heartedly recommend you do do it at some point. I honestly didn't find the recovery to be all that bad, and I am thankful for it every time I walk into a Victoria Secret and buy a bra without trying it on first. Pre-surgery, I had to custom order my bras at $120 each.
"Of course its hard, if it were easy everyone would do it. Hard is what makes it great"
-League of Their Own