I think Magnus was about that weight at that age... He's now a lovable teapot of 16 lbs! Please know that even though some yorkies might not have the "standard" yorkie look, it doesn't mean they're not pure yorkies.
I bet you'll fall in luv (I'm sure you already have) with ur lil guy no matter how big/small he gets.
Congrats on the addition to the family!