My dr told me not to use those charts, they are out of date and were made in the era of mainly formula fed babies.... my ds was 11kg at 1 year old and now hes 2.5 yrs old and only 12kg, so i wouldnt worry.

If she is eating and on the breast still I wouldnt be concerned, is she able to hold her own weight on her legs yet? stand up etc? (DS couldnt til 12 months but some girls are quicker walking )

I agree with Starfish, As long as she is making all her milestones other than weight... Id relax