Erin,
I don't have an actual Cushings DX but I know a few months ago when my Neuro decided it was time for the pred to go he said I was "cushingoid" I was so swollen in my face and stomach. I looked like I was pregnant some days from the swelling. I was also incredibly depressed and had not had a period for months until this week. As for how low you have to go, I can tell you once I dropped to 15mg every other day my symptoms started getting better. I have lost about 10 pounds and my swollen stomach has gone down, I am sleeping again, depression is much better and like I said I am having periods again. I am now down to 5 mg EOD and feel like my old self again. The MG weakness is worse but nothing I can't control with rest and Mestinon. I spent the last 9 months feeling like someone I didn't recognize anymore. I was so irritable and my poor family was probably scared to death of me. I will take the weakness any day over the effects of the pred. You might talk to your neuro about taking 35 mg every other day instead of 20/15 My neuro swears the every other day plan causes less side effects. Hang in there, once you get down a little more on the pred you will start to feel alot more like your old self.
Kendra