Sorry to hear you're struggling and didn't find a satisfactory resolution with your testing. I can tell you that I totally identify with your experience. Like you, my reflux was creating unhealthy lungs, and like you, I had a low DeMeester score--at one time, just 4--and my GI doc said with authority, that my reflux was not causing my lung issues.
Fortunately, my PCP did not accept that opinion, and although it took several years during which my lungs were in horrible shape and I was taking unhealthy amounts of steroids to keep breathing. My asthma doc says that GI doctors only look at how reflux affects the health of the esophagus and pretty universally don't have any idea that a very small amount of reflux can create havoc with the lungs.
I suspect your ENT is more keyed to the more atypical affects of reflux, which is why he/she is treating you more aggressively.
This is not going to be an easy road for you, but don't give up. Hopefully you can find a healthcare advocate who is knowledgeable about the harmful affects that of small amounts of reflux have on the lungs. After my lungs continued to deteriorate, I finally (with the help of my PCP and asthma docs) got a GI doc to take my condition seriously. Keep in mind that I never had more than a borderline DeMeester score. <14 is normal, and my worst was 14.8.
Those of us with atypical symptoms face a lot of resistance as we seek help from GI docs. I ended up with having a Nissen surgery, and it healed my lungs. I have allergy-induced asthma, but it is now in control...my steroid inhaler dose is a fraction of what it was prior to my surgery, and my lungs are doing great.
A GI doc once explained their reluctance. Their fear is that they may recommend surgery and the surgery won't help. It's a tough call. I understand that. Still it's really discouraging when you're trying to find a solution to some serious symptoms and aren't getting any help.
You have my sincere sympathy!
Hang in there...don't give up! There is help out there for you.
Words of wisdom by Eckhart Tolle:
"Whatever you fight, you strengthen, and what you resist, persists.”
“Worry pretends to be necessary but serves no useful purpose”
“Accept - then act. Whatever the present moment contains, accept it as if you had chosen it. Always work with it, not against it.”