My Gracie weighed 1 lb. 13 oz at 8 weeks. Her parents are 4 and 5 lbs. The vet said she still might be in that range, but might be a bit bigger. They go through growth spurts. Here is a link to a growth chart that is reportedly fairly accurate. It put Gracie's adult weight at 5.5 lbs. When I approached my breeder about this, she said Gracie's mom never had pups that got larger than 6 lbs.
http://yorkiepassion.com/growthchart.htm