What Breed is My Dog?

We just rescued a 10 week old puppy. They said he was a Sheltie. He weighted 8lbs and has a tail that curls. I took him to our vet and she said he is a German Shepherd mix. What do you think he is? We thought maybe a Golden Retriever and Shepherd mix or Shepherd and Collie. I need your help.

By L Murray from Fairview, PA