She's now eating fine. At one time I ground kitten food finer than adult food until I realized, kittens in the wild have to learn to eat whole prey. Unlike dogs, cats do not regurgitate food for their kittens. Kittens have sharp teeth and strong jaws for a reason. Except for Rooney, who's a big guy, the rest of my cats are smallish.
Purebreds tend to be smaller than domestic cats.
The size prey cats the size of mine would normally kill is much smaller than conventional chickens. I feed chunks of food and bone from ribs. Regular size chicken bones are too hard for most cats. Cornish Game Hens are perfectly fine to feed, bone and all.