Is there any helper grandma or nanny to help taking care of your baby. As your baby is premature and on top of that having reflux, it must have been taken a toll onto both you and your wife...

Parents need to get enough rest as well especially your wife so do employ and get someone to help out to offload you and your wife

As you mention, you already consult few Drs. If you have consult 3 or 4 including both government and private, I think there is no need to seek others. There is very little diagnostic that the Pediatrician can run at this time. If the situation did not improve after 3 month old, maybe the Dr will look more closely into the baby digestive system and etc.

So... stay clam, get enough rest for both you and your wife.