Welcome
What kind of food is she eating? A lot of times skin/hair issues can be traced directly to the type/quality of food.
I'm glad that the vet says she's healthy so far, a lot of times a not so good breeder will sell what ends up to be a very sickly puppy. I hope Hailey's health remains good and that her thinning hair is fixed. Please post pics, would love to see the little cutie pie