TrUST yourself, Julie. No one knows her better than you - and she knows that you are looking out for her.
As far as her appetite - remember that a cat in high blood sugar is getting mixed appetite signals to their brain.
Here is a great post on feeding a cat as much as they want. The best thing you can do is to let the scales guide you on feeding her. If she is losing weight and shouldn't, then feed her a little more. If she is gaining weight and shouldn't, then feed her a little less. Her appetite alone can't tell you the amount to feed her.