Obsessing about a Yorkies weight is ridiculous in my opinion. It's as dumb as our yorkies saying "Gee I hope mommy doesn't grow over 150 pounds."
I mean really, who cares? They love us unconditionally no matter what we look like so we should do the same for them. I could care less if Nikko (who is 5 1/2 pounds) grew to 10 pounds tomorrow. He is a sweet and healthy little boy. Isn't that the most important thing?