Thanks for the update @camomma. It's always good to hear how people who are doing especially who have previously commented. I certainly didn't expect this post to blow up like it has over the few couple of years! I never realized how much of a widespread issue this is, but glad that we're all here trying to help each other out.

I also had a lung function test some time back, and usually it'll check lung capacity and your ability to exhale forcefully and volume of air you inhale. It's a common way to check for asthma, but can also check for other things like COPD. I had normal numbers though they were on the lower end of that. I can't remember what that number was, but it had to do with tidal volume and capacity of the lungs holding air, and also velocity of air when exhaling. It will be interesting when you get those results back.

I may have asked this before, but have you looked into breathing exercises like the Buteyko method or other methods? It helps me to stabilize the air hunger feeling so that I don't feel the "empty lung" feeling like I used to.

Wearing a mask may have an effect on your breathing, but hard to tell. I don't know a whole lot of what effect masks have on breathing over the long term, but if you can breathe through your nose as much as possible even with a mask on, that could help.