The common wisdom about tapering xanax is to do it slowly. You seem to be on that path, so staying on 0.5 for another week, and cut in half is about right.
YOu should talk to your doctor about another method, which is to switch to a longer acting medication,like klonopin, and then taper off of that. But since you have already reduced your usage to one at bedtime, the course you are on is probably better.