I can't know for sure, of course, but I wonder if you're having difficulties with the site and are unable to respond to my questions? I can't see things from your end of things and I'm not responsible for site issues of this sort but my apologies if that's the case.
I'll go ahead and respond back to you in hopes that you can access my reply since I know you're terribly worried about Bella.
I can understand your concern about giving Bella steroids on an empty stomach but if you gave the Sucalfate first, then, hopefully, we won't have to worry about gastric issues. Even if you didn't, not all dogs will vomit or experience gi issues when steroids are given without a meal.
As I'm sure you realize, steroids are the gold standard for treating her condition so it's important that she continue receiving them.
If she won't eat or drink on her own, then you may need to force feed her. One method would be to mix canned food in a blender with water or low sodium chicken broth or, even better, pedialyte to the consistency of soup. Then use a small turkey baster or syringe to dribble this mixture into the side of her mouth where there's a gap. Hopefully, she'll tolerate this so that you can continue to feed her this way throughout the day.
You won't need to worry about her not drinking on her own since you'll be providing fluids in the mixture. You could supplement if you wanted by also dribbling plain liquid into her mouth.
You could also soak dry kibble in the aforementioned liquids for 20-30 minutes and then blenderize this with more liquid. Either way should pretty well.
You could also offer her human baby food but just avoid those with onion or garlic in them. She may not find this food more palatable than what she's been eating but it's worth a try.
I'm sure that your vet mentioned that the prognosis is variable in the patients and may be guarded in many cases, unfortunately:(
If she doesn't start to eat on her own, then a recheck may be prudent. Deb