Maybe this is just the way he is meant to be, but HVs, doctors, nurses etc don't see it that way do they? It's like, if they're not fat, you're doing something wrong!!
It took til DS was at his 12month checkup before the doctor acknowledged that DS was fine being 'skinny'. She was forever telling me he was too small, not gaining enough, would be developmentally delayed and all sorts... once she saw he'd met his milestones early, etc. she said he was fine and not to worry about his weight.
Only other thing I can think of right now is that perhaps he has wind and he's feeding to try to get rid of it, but in doing so it's giving him more and you're getting stuck in a cycle.
This is something we had with DS too. Its a vicious cycle.
If he is happy within himself and meeting milestones and everything except the weight chart says he's fine, he is fine.
Hugs xx
