Oh dear, I think my DD is a hefalefalump! DD is a little over 11 months and I think she weighs (at a guess) about 13 or 14Kg!!!! BUT, she is also a very tall girl and is in perfect proportion (well, maybe not PERFECT proportion... she is getting a bit of a belly!
Seriously though, I don't worry about weight - especially since I agree that once they are more active, their weight evens out. And I would much rather encourage healthy eating and lifestyle than obsess about weight.