Sophie will be 19 weeks on Monday. I just weighed her yesterday and she was exactly 5lbs 8 oz. Now, Chewy (her brother, same age, same litter) weighed 6lbs. 7 oz! He's a chunk!
But he's built much bigger than Sophie is.
If they continue to grow like they have been for the first 4.5 months of thier lives, I figure Sophie to be at least 7.5-8 lbs & Chewy to be 9-10 lbs. But that's just my estimate. Their mom and dad were both on the larger side (I'd guess around 7-9 lbs).