Have a friend who's little boy fell off the charts too. He also took a long time to drink a bottle.
They ended up in ED for a flu he had and they decided to do further investigations and found he had enlarged tonsils and adenoids so they removed them and he put on heaps of weight and drank and ate in what would be considered a normal time. He has other issues as well, it doesn't impact on his size though just his development which you don't have a problem with.



Or it could be that you just have small kids..my DS1 was and still is always on the 5% and is still small, eats more than I do! His Da was always the smallest kid, the one who holds the sign up in the photo's then at 16 he had his growth spurt and is 6ft!