Well here ya go I happen to have a pic of 3 babies and can explain thier weights. All 3 of these come form the same parent different litters. Dad is 5 lbs and mom is around 7
The dog on the left is Ada, she is 1.4 yrs old and weights 7 pounds.
The monkey in the middle is my Diggy he is 4 months old and 3 pounds.
The dog on the right is my Bella she is 2 years old (June 9th). Now she was 6.0 pounds in the winter. Then I introduced Diggy...well she eats more now but is so much more active. She was 4.11 last Friday at the vets. It seems like a huge weight loss but I switched her to home cooking and all holistic foods and from commercial treats to fruits veggies and natural healthy treats. As you can see she is very tiny framed...that's her laying on the couch with Diggy and she is not much bigger than him! Weight loss and weight gain totally used to freak me out...I had like a 45 minutes visit/chat with my vet she is just AWESOME young, vibrant, and always willing to get to the bottom of any question I have. She goes by the curve in dogs rib cages...if she can feel the curve they are fine..if its a lil hard to feel they are a lil cubby and if she has to really press to get to them....TEAPOT! lol She has always said Bella has the frame of a 3.5-4.5 pound yorkie. so she even now is still a lil chubby But I refer to her as "buff" she is solid muscle and vet says she is fine
) I know what it feels like to stress over weight, food, sleep, everything over you baby. I hope this helps you even a lil bit. If your baby is eating, drinking, has wet nose, playing, and nice healthy pink gums. I think she is fine. Yorkies are no different than us.... Some eat and eat and never gain....some never eat and are over weight!