Awww, look at the big guy! And he looks so LOVED, too!
Yes, the yorkie "standard" is seven lbs or less.....and increasingly, people are wanting them smaller and smaller. Since that is where the $$ is, lots of breeders are deliberately trying to breed them that way....frequently to the neglect of the health and safety of the dogs.
Yes, at 15 lbs, he *would* be considered a "moster yorkie".

But, yes again....lots of people here do have "teapots".

So he's not the only one, by any means!

I doubt you'll find anyone here who would revoke his "true yorkie" status.
I have one that is less than four lbs, and we are alllllways having to focus on not hurting her. I bet you *are* happy to have your big guy who's tough enough to take some hard lovin'!