What Breed Is My Dog?

Some tourists from my mother's workplace found this lovely female puppy, Minka, in a park next to her workplace. She brought it home to take care of it until we find if she has an owner looking for her. In the end we decided to adopt her, we assume she is around 3 months old, but we don't know what breed she is. Most probably she is a mixed breed of German Shepherd and something else. Some people say she is mixed with a Labrador and some with a Beagle. Also some people say that she won't grow up to be a big dog. Can anyone identify what breed she is?