When Cheyenne was 6 months old, she weighed 35 lbs. When she was a year old, she weighed 50 lbs and she's always hovered around that. She kind of grew up and then filled out (especially in the chest area) after the first year. It was kind of weird - even though she didn't gain a lot more weight after her first year, I guess it was redistributed or something!
I don't know that I would feed her more than is called for unless she is more active than most puppies. You don't want her to get too heavy, too fast.