Trying to wean.

I have been taking Advair for about 2 years, and I also quit smoking right around the time I started (and was exposed to lots of animal allergens in a vet clinic). I have since stopped working with animals (although I do still have 2 cats), and I have been trying to wean off the medication. It seems that, while I can keep it down to one dose per day, if I let it go any longer than that, I have really bad asthma attacks. Am I going to be stuck taking this forever? What if I can't afford it and run out at some point? I am really paranoid about being dependent, but I don't know how to get off the stuff. I was thinking possibly a short course of prednisone or something. Any experience or advice would be great. Thanks.