Baby Bottle Nipple Issues

My one son (Twin A) was in the NICU for 104 days. There were many delays in getting him to eat by mouth, eventually he didn't want the bottle for more than 1 oz at a time. The staff wanted to get him home because they felt that if he spent any more time with them in the NICU he would start to suffer developmentally. So my husband and I agreed to have a G-Tube placed, long story short when he came home 2.5 weeks later because of complications with surgeons messing up, which lead to another G-Tube being placed and an infection in the old site. (Making my husband and I feel awful about agreeing to the G-Tube in the first place.) Consequently he had no interest in eating orally, taking at most 0.5 oz at a time.
When he came home, we felt he would have more success because we would be able to feed him orally more frequently then the NICU nurses could. (We were at a high bed NICU where a nurse could be responsible for up to 3/4 babies at a time.) Plus they would only feed him by mouth if he was showing cues, sometimes he would show cues halfway through a feed and they wouldn't heat up more milk to try by mouth. Nothing against them it was their protocol to follow. We just felt we could feed him when he wasn't showing cues or at least have some ready if he would.
Anyways, we started to feed him with Dr. Brown's nipples, his twin (Twin B) took to them right away when he came come from the NICU after 60 days. So we felt that Twin A would do the same.
Twin A has been home since Sept. 2 but hasn't improved with feeding at all, if anything he's doing worst orally. We've tried different bottles besides Dr. Brown's (NUKs, Avent, Phillips, Tommy Tippy, Mam are the ones we've tried). He was doing some breastfeeding in the NICU but won't do so anymore.
Anytime a nipple comes near his mouth, he barely opens it. If he does his tongue is on the roof of his mouth. When we're finally able to get the nipple in his mouth, he sucks on it for a few seconds. Spits it out, along with any milk that he took, and screams in our faces. He'll take a pacifier. We've tried tricking him, doing a switch-a-roo, but that doesn't work. We've had mild success with dream feeding. Maybe taking 5-10 mls then. After he calms down we try again, we bring the nipple close. He tries to suck on it, we get him to suckle for a second or too and he spits it out and screams.
Therapists come out to the house to evaluate him every other week. We're seeing a feeding clinic next week to evaluate him. But I was hoping someone has had a similar experience and maybe give us some of your tips?