I see that you have been trying to find answers for 9 months with testing and examinations. Being unable to take a deep satisfying breath is really scary, since the ability to do so is supposed to be automatic. Even without a diagnosis, sometimes there are things to do to make yourself feel better. Let's see if we can find something to help you. Aside from no affirmative diagnosis, what recommendations as far as lifestyle, diet, exercise, etc have you been given so far?

I have chronic SOB from long term asthma and another lung disorder. I uses "belly breathing", yoga breathing and other techniques several times a day to help with it. If I skip even one day, I find I am miserable. If you scroll to the top of this discussion, you will see that there are breathing techniques that are often helpful for shortness of breath (SOB) issues.

May I ask if you are spending your time in a recliner? My (very direct) pulmonologist would tell you "get out of there" and sit upright, with good posture or stand up so your lungs can expand properly.

Have you seen a therapist for help to learn breathing techniques, or watched a video and tried them? When I was first using the exercises, it took at least 2 weeks of 4 times a day to get relief, so it is not an instant result.

Let's see if there are others who want to offer suggestions here too.
Sue