I think someone else already said this, but I just wanted to add that it IS possible if she is tiny that she is older than you think. I have had really tiny pups that didn't get their teeth in until later than their siblings. I had one last year I kept until 6 months old. It took her 4 months to get in all her major teeth...and I KNOW for a fact she was 4 months because I delivered her.

So it IS possible, although in your case she may really be younger. She is adorable!!!