I'm very familiar with Cushings, bc Wylie has Atypical Cushings. As you're probably learning, it's a very complex and confusing disease. It sounds she is having the excessive peeing...is that right? So is she also drinking excessively? Those are both cardinal signs of Cushings -- as is excessive hunger, pot belly, muscle wasting, hind leg weakness, HAIR LOSS (big one!), ongoing skin and ear issues...and the list goes on and on.
Cushings is prominent in Poms, btw. It's smart to get her off of all steroid like meds bc you can't get a true diagnosis of Cushings w/ steroids in her system. If she has steroid-mediated Cushingoid symptoms -- then all that will go away when the steroids clear her system and things balance out.
There is no special diet for Cushingoid dogs - just feed normally. If she has the pot belly and/or has gained weight, don't restrict her food - the hunger is so bad with Cushings that I'd just wait until you get a diagnosis. At that point, that's when you address her weight...if it's even an issue. The proper treatment will in turn treat any weight / hunger symptoms.
This is a great overview for Cushings:
Cushings (Hyperadrenocorticism)