Wow- if you have a vet saying that 1.7 lbs makes him too big to be a yorkie, I think it's time to look for a new vet. He obviously can't tell the difference between a yorkie and a hamster. No doubt he'd think my Rhett (10 lbs) was a horse, LOL.
Shots can definitely hurt. Like people, every dog has their own level of pain tolerance.
And yes, pure bred yorkies can have white on their chests and paws as puppies.