I had a similar situation happen when we adopted Sully.
Sully's mom was 7lbs and his dad was 6lbs. Brenda, our breeder, told me that he wouldn't get over 7lbs.
Sully now weighs 9.3 pounds. Oh well! We couldn't love him more though! He has a place in our heart that coudln't get any closer even if he did shed 3 pounds, hehe!
I called Brenda and told her, just so she knows, that Sully wasn't the size she had told me....she gasped! She said he must have had a big grandparent b/c she hasn't had a 9 pounder in a while, haha!