Welcome to YT. You've definitely come to the right place for Yorkie info!
My guy is 14 pounds --
twice the size my first Yorkie ever reached.
Don't worry about it. I always thought Ozzie was a freak of nature, until I found YT. Not only are there other Yorkies around his size, some are even bigger.
And ignore people in public who may ask you stupid questions (Are you SURE he's a Yorkie? is chief among them) or make snide remarks about him being bigger.
Just feel lucky to have all the benefits of the breed inside a heartier -- though still small -- body.