The whole "pet store puppy mill" thing is simply not true. The USDA has rules about puppies that are sold at petstores coming from registered breeders. They have to all be vet checked at least twice- usually more by the time they reach the consumer. Puppies sold in petstores have (by law) seen a vet, been vaccinated and wormed, and are free of diseases that could endanger humans to the best of the ability of the vet who signs their health certificate to know. They also have to be cleared as basically healthy for sale. Peta and others have been pushing the whole "poor puppy mill" propaganda for several years just to further their own political anti-breeding agendas. And because most people are not really familiar with the legalities of breeding, they just believe what propaganda they hear then pass it on as truth.
Realistically, this dog is simply a pet quality dog. There is nothing majorly wrong with her at her sale or the vet would have picked it up. Does that mean it is guaranteed that she will never have a genetic problem such as hip dysplasia? No. That is not something a vet would pick up on a very young puppy, and she is a pet quality puppy. She will never be the quality of an AKC champion, but she is what she is. She is a wonderful, cute companion ready to love you with all her heart. She is a pet not a show dog. She may have some genetic problems show up as she ages, but that is true of any pet quality dog.
If you are concerned about her being a purebred, you can send in a DNA sample. It costs about a hundred dollars. They are pretty reliable. It still would not make her a champion quality dog. She is a pet.
I personally think the dog is adorable.