wow your baby is going to be a big girl here's a growth chart that i went by for coco and it is right on...personally i can see your baby growing over 10 lbs easy if she's 7 lbs at 41/2 months she is gaining 1 1/2 lbs a month. they don't stop growing at 6 months but they due slow down dramatically after that. the growth after 6 months is barely noticable that's why alot of people say that they stop at 6 months.
http://yorkiepassion.com/growthchart.htm