I'm sorry you are going through this with your cat, it must be very scary for you.

Cats cope with steroids (prednisolone, not prednisone) very well, better than humans, and can be on them for years. I've fostered cats with asthma and early onset arthritis, and prednisolone was the only way to give them a good quality of life, and for many years. It's called the "feel good drug" and does make cats feel generally better. Just make sure she gets plenty of fluids. Does she eat wet food?