By about 5-6 months depending on breed, a chick is pretty much done with the quick growing and from here on out they will mainly be filling out rather than growing taller. If you had her since she was a fuzz ball then she should be about done growing and starting to mature. I have nothing to go off of for size comparison but chickens come in all sorts of sizes so without knowing her breed (if she is a pure bred) there's no way to know if she is the right size for her age. If she is happy and healthy while being fed a good diet then I would assume she is doing well. As a side note I see no need to feed medicated food to a fully feathered healthy bird. Once the bag is gone I'd switch to an unmedicated starter/grower.
Looks like the comb and waddles will be developing more color and size before long.
