Really fed up of 21 month old not eating. Any advice?

[Thegandernotthegoose]

Ds has always had problems with food. Had pain and reflux on milk feeding as a baby. Started on paediatric advice to wean at 4 months. But unlike every other reflux baby I have come across ds has never really taken to solids. We use to be able to get okay amounts in him sometimes by entertaining him and spoon feeding him (he always had food he could feed himself with but would only eat a few mouthfuls before losing interest). However now that he wants to be independent he refuses to be spoonfed but STILL only eats a few mouthfuls before refusing to eat any more. Then half an hour later he will be hungry but point black refuse to eat solids but instead cries for milk. As a result he is still bottle fed at 21 months. We only give this as a last resort but he still gets two or three bottles a day. We have tried 'starving' him into submission on HV advice but this just resulted in him refusing to take anything and after five days he was so constipated through dehydration that his anus tore as he tried to poo. So not doing that again.
Ds is otherwise active and healthy though tiny. He started off in the 50 th percentile but is now in the 0.2 percentile and very obviously small compared to his peers. I can see other mums surprise when I tell them his age.