Vets are not all "created equal"...finding a competent feline Veterinarian would be my first goal if I were in your position.
You said you have planned to take her to another Vet...if you are open to suggestions, you might want to consider checking out the Vet listed on
this site (a list of Veterinarians who have been recommended by the "owners" of chronically ill cats).
Most Vets are fine with everyday, run-of-the-mill, relatively minor health issues. From my experience, there are very few who are willing/able to go the extra distance required to competently diagnose and treat issues beyond those.
One of my immediate concerns with what you're relating is that your cat isn't getting sufficient caloric intake to sustain herself. When this happens, a cat faces the prospect of developing another life-threatening condition commonly known as "fatty liver disease"...in the absence of sufficient nutrient intake, the liver begins drawing on body fat. Unfortunately - only in cats, BTW - the liver "bites off more than it can chew" and the result is that the liver itself turns to fat. So, my recommendation would be that you move on this ASAP!