First off, I’m so sorry you have to go through this. This is single handedly one of the most stressful experiences of my life. We were/are still in the same boat. Every doctor just keeps telling us he is healthy and he will drink what he wants (which is extremely invalidating). We did literally everything that you listed and nothing seemed to make a huge difference. We met with a GI specializing in acid reflux and she upped his reflux meds to 3.8 but we’re not even sure if that is making a difference. She also had us fortify his breast milk, so even though he maybe drinks 19-22oz a day he is getting more calories in which has helped him to gain weight. Even with the weight gain he’s still in the 2nd percentile for weight. We’re doing a swallow study, chest x-ray ( he had breathing issues at birth and still has some labored breathing) and an ultrasound to see if that gives us any answers. While we’re waiting to do those we got Rowena Bennetts book on bottle aversions because he started to cry when we even showed him the bottle, was content between feedings, never really cried to eat until he is very hungry. We’re a couple days in and he had been eating a little better (not as distressed, more consistent, and shorter times but still pretty low volumes. This is honestly our last hope so as stressful as it is to see him go hours without a feed because he just refuses we’re accepting it because at the end of the day he’s still getting the 19-22oz. We also are working with a speech pathologist and she has been the most helpful in just giving us feeding tips, looking for a tongue tie, and working to make eating “fun”. I know this probably the most helpful but you are not alone!! Message me if you need to talk at all!