I have two resuce kitties - one is part maine coon and the other is a little fuzzy unknown. I feed both of them Royal Canin dry. My vet said it is a good quality food and my two thrive on it. They are also both fussy eaters. I mix two kinds together - Royal Canin sensitve skin and Royal Canin Maine Coon.
You could try and switch your kitty over to Royal Canin - I'm sure they have a kitten food.