She is still a wee pup. So glad to hear your Yorkie has a very good appetite.
I can only say monitor the amount of food you are giving her, not too much, not too little. Always err with a pup on the more side of food.
I don't know if Casear is a good food or not. I home food my beasties..so not too "up" on the best kibbles and wet food out there.
One way to monitor take a look at her weight right now... feed about 10% of her current body weight. Lots of activity... then feed a bit more that day.
Remember treats do count on the caloric intake per day.
I have a couple of large dogs as well as my Yorkie. And I can tell you our male would eat us out of house n home. 2 Christmases ago he got the turkey off the counter, and was busy chowing down on it before I caught him.
Our large female I have to entice to eat. Hard to keep weight on her.
Razz is like your Hazel a right little piggy. Nobody is free fed here. I monitor all the time the intake. I don't want fat dogs.
But again your wee one is a pup. Err on the side of overfeeding a "bit".
In the final analysis, some maybe many doggies are little piggies. They'd eat till the cows come home. Sounds like Hazel maybe one of those.