Ha! That's nothin'! My little Jackson is 12 1/2 weeks old and already weighs 4 lbs.! He still has ALOT of growing left to do! lol 7 lbs. is still within the standard, but even if your baby gets bigger than that, what does it matter unless you're planning on breeding?
My other yorkie is 4.4 lbs. full grown, and he is VERY tiny. Although he is very healthy, he has always seemed somewhat fragile to me (even tho he's not). Jackson, on the other hand, is STRONG! Nothing even remotely fragile about him! lol
Size is very unimportant to me because I am not breeding them or showing them, they're my babies. They are healthy, and that's what matters to me.