The 12 week rule doesn't always apply though. My Riley was already 4 pounds at 16 weeks and now as an adult of almost 4 years old he weighs 4.2 My boyz both stopped growing around 5 months. I think you have to take a look at the parents, grandparents and great grandparents of your puppy to get a better idea of where they might end up...genetics plays an important role in their adult size. Small parents can always have a throw back puppy to a member down the line somewhere...kind of like having a red headed baby when both parents are brunettes.
