Maybe Syd just had strange growth spurts...but she was 2.75 lbs when I got her at 8 weeks and she grew to be 6.5 lbs full grown. Your yorkie may not be huge. Maybe just 7 or 8 lbs. But she definitely will not be 4-5 lbs like the breeder told you. Honestly a 6-8 lb yorkie is a good weight. You won't have to worry about her being as fragile.