I've heard great things about Royal Canin Gastrointestinal for pancreatitis dogs. It's an RX food, so probably going to be a bit more pricey. Jackson had a sampling of it once during GI upset, and he loved the taste.
Also, California Natural makes some great very very simple and very low fat formulas.
I believe Canine Caviar also has a very low fat food.
Sorry you're going thru this.
I hope she feels better soon!