If she appears to be well, I think you are okay waiting until her one-year vaccinations are due to talk to the vet. The doctor will evaluate her body during the routine physical exam. Be sure to ask if she/he thinks your pup's weight is appropriate.
My younger boy Teddy was a skinny pup. His bones almost protruded under his skin. Most Yorkies will develop more fully in their second year, and Teddy did as he aged. He is still finely built compared to my other boy.
You should be able to feel the rib cage without pressing too hard, and you should see a waistline when looking down onto her back. That is normal. If you can visibly see her ribs and spine sticking out, then she probably needs to gain a little weight.
__________________ Kristin, Max and Teddy  |