Hi Banjo!
to YT!
Oh my, your little guy sounds like he's growing like a weed! We call those larger yorkies...teaPOTs! LOL
Why are you suspicious about the age? Do you actually think he was younger than 7 weeks when you brought him home? 7 weeks is actually VERY young as it is...smaller breeds of dogs do best when left with their litter until at least 12 weeks of age. Sounds like your guy's doing pretty well with you though and you've done a good job of raising him. I hate to tell you that he will probably keep growing until he's a year old...so he's still got a lot of growing to do! You should feed him according to his weight, so don't be shy to add more kibble as he gets bigger (as long as he's not getting fatter).
Have you seen his parents? Do you know for sure that they're both pure yorkies? It sounds to me like he might be partly another type of terrier. Can we see pictures? (pretty please??? we love pictures!!)
As for what a 12 week old puppy looks like, this is my pup that I will be getting in a few weeks. He is 12 weeks in the picture, he'll be 15 weeks when I bring him home. I can't wait!
Oh - and lastly - you may want to post your question again in the 'general' forum because our poor little canuck forum gets very little attention unfortunately.
Good luck!