I noticed her legs, too! In fact, I had to re-read the post because I wondered “what breed of bird has those jet black feathers and heavy legs? “I too would be a little concerned about her size. It may be just the camera angle but she does look quite rotund and that could make her neck appear thinner, but it could also be a mini moult.
What do you feed them and are you sure she is just 9 months? Her legs look like those of a slightly older bird.