Been there!! Our Toto's appetite got so picky, she was driving us crazy! She got to the point where she didn't want to eat the same thing two days in a row!! Then started refusing anything that even resembled meat ... only wanted veggies! Long story short ... her tiny 3 lb. frame packed on over two extra pounds and our vet chewed us up one side and down the other!!
She said that we had to get the weight off and that she absolutely would eat when she got hungry! She gets 1/8 cup Nutro Ultra [weight control] in the morning and 1/8 cup in the evening. I keep about 1 tablespoon Royal Canin Yorkshire 28 dry available each day ... some days she eats it, some days she doesn't. She gets 3-4 liver treats daily and a few Yogurt Drops. The vet said to only give her Nutri-Cal is she appears a little hypoglycemic and she would be fine. The importance of keeping the extra weight off is because it puts extra strain on her little heart and her knees. I have to find a way to provide extra exercise for her because she has become quite the little couch potato!
Toto will be 2 yrs. old next month, so you should discuss Maggie's diet with your vet, but ours was absolutely right when she said "when they are hungry, they
will eat!"
Good luck!