My daughter only weighed about 4.8kg at 6months!! As long as she is growing in proportion, and eating well, i wouldnt be too bothered!! I saw a little girl at the drs the other day, full term bub who was smaller than my daughter. She was prolly about the size of a newborn!! Her parents just said she's always been small, and there's nothing at all wrong with her!! Dontstress, im sure your DD is beautiful, and just perfect...