Talk to Gynecologist on NG Tube Baby/oral Aversion

My baby has been on NG tube since birth. We are doing his PT and he has developed oral movements. The problem is his strong oral aversion no matter what we do he resists oral feeding. Two days ago he pulled out his tube and we decided to feed him only orally. He is 9monts old, weighs 7.6 kgs. He was on 700-800ml formula/day feed. His feed over the last two days has dropped down to 200-300ml. We are looking out for signs of dehydration so far he is doing good. My question is how much weight loss should we tolerate before giving up? And what can we do about his oral aversion. The problem is with NG his "oral feed l" drops down to zero. We can work on his sucking through massages but his swallowing will only improve if he swallows. The more his grows the more his daily ng intake will increase. I can already see signs that we are becoming tube dependent. There have been cases where cold turkey NG removal has been successful. We have been consulting neurologist, sperch therapist, occupatio