Poor Harley, but at least now you have a diagnosis you can start to help her.
I don't have experience of pancreatitis in dogs but I am feeding Molly a low-fat home-cooked diet and finding it easy to do (though a bit pricey). I buy frozen white fish (pollock) and feed with mostly low-glycemic vegetables (broccoli, spinach, green beans). I also feed chicken with the skin removed. Molly has an egg twice a week and minced beef (5% fat but with all the fat drained off). She also has a small amount of tinned sardine a day but I imagine that might be too high in fat for Harley.
I'm not feeding any grains, apart from the flour in the liver cake I make (45g per day of which 15g is flour).
Apparently it's important to add calcium so I grind eggshells and add a teaspoon of that a day.
I'm feeding 2% in weight of food of the weight I would like Molly to be.
While you look around at commercial foods or research home-made, I don't see why you can't feed Harley white fish or chicken with the skin removed plus veg, as it won't matter if it's not a completely balanced diet for a few weeks.
I hope you can get her more comfortable soon.