Normal size for 8 weeks. My dogs have never followed the yorkie growth charts. Gracie weighed 2 lbs, 3 ounces at 8 weeks. At one year, she weighed 4 1/2 lbs and today (she's 3 years), she weighs 5 1/2 lbs.
I can't remember London's weight.
But she currently weighs around 6 1/2 lbs.
Dallas weighed 1 1/2 lbs at 8 weeks and at 5 3/4 months, he weighs 3 1/2 lbs.
Your best bet is to look at the parents. Everything about these dogs involves genetics. Don't get me wrong...a tiny pup that comes from average sized parents could end up to being large and vice versa.
Pat is right, though. Don't expect a 2 lb 8 week old pup to only get to 3 lbs. Not going to happen.