She could just be from a really shy mother. I have a feral dog that had 4 pups last year on the street. We used the pups to catch the mom and even though we've had the pups since they were 2 weeks old, a couple of them were very shy and skiddish in new situations and around a lot of strange people. At home they are very outgoing with us, but trying to get them adopted out has been a challenge. We still have one a year later. He opens up a lot when we have him at adoptions and he can play with another dog. These kinds of dogs usually bond best with one or two people at a time. You just need to give this pup time and patience and she'll come around. Try to spend some time with her on her level i.e. you on the floor with treats.