DS is 3.5 and 13.5kgs. He eats well enough and I didn't crack 30kgs til about grade 10. Going by that, he fits into our family perfectly. He has my fast metabolism and eats little and often, like me.

What are yours and his dad's body types? Does he stand out against the rest of the family? Is he extra picky with food or just not overly interested?

I know with food that it can seem like they're not getting much, but keeping a food diary is awesome...I did it for a few weeks with DS and realised he eats more on certain days, and at certain times of the day. Over an average week, it evens out. I also make sure that what he does get isn't empty calories. As for the sickness, work on his immune system.

Meant to also say that, if, after you've kept the food diary, you're still worried, at least you have something to show the doc.