You say there were hundreds of dogs at the breeders...are you sure it was not a puppy mill? I don't think a responsible breeder would keep hundreds of dogs. So with that in mind, my first suggestion would be to take your puppy to the vet to check for a bladder infection, and get her checked over. The feeling comfortable around you for 2 to 3 weeks too suggests puppy mill to me, the puppy had very little (no) human contact in its early weeks. Get her physically checked first, and if/when she's OK the bladder training should hopefully go better. How's the pooping training going?