If it makes you feel any better.. I did the happy dance when Remy reached 4 lbs. She was so skinny and I did worry. She kept gaining and now at 3 years she is over 5 lbs. I am thinking that is her healthy weight..solid not fat.
My guess is your little one will be somewhere between 3 and 4..double 12 week weight and add a pound. That is very small but you are a great yorkie mom and she will be fine
btw...we do the "yorkie shuffle" in our house.