I get really disgusted with weight obsession, and it amused me, Nicole, that you were writing about wieght, lolol, because I know you have been on here long enough to be tired of it, too.
I understand that if you are a breeder, your needs are completely different. But anyone buying a yorkie as a pet needs to get real. Why would a breeder give up a "perfect" dog? They wouldn't. So you get the imperfections. And no breeder or anyone else can exactly guess what size any pup is going to be.
Acceptance of your pup, loving them as hard as you can, and being happy with your choices are what makes the difference. Just relax and love your yorkie, regardless of size.