My 20 month old DD, Alex, only weighs 9.7kgs. Haha we always wonder when she will hit the 10kgs!! Maybe by 2 but I doubt it!! I had it all checked with our Paediatrician and he said she is fine! They use different charts to the one's in the back of the heath books. She was on the 25th percentile for all.
My 22 month old daughter weighs 10.4kg. She was only 8kg when she was 12 months. Her playmates were heavier at 1 (around 11kg) they are now only about 12 kg, it looks like Gabrielle just put on weight later. She is VERY active and always has been and my mum says that i was 'petite' when i was little too. Shes been a snacker but is now starting to actually eat a meal 3 times a day (at least) so as long as there is food going in and waste coming out i guess she is healthy. I too don't panick about 'bad foods' i just think that as she gets older we will teach her the difference between treats and otherwise.