I think they take into effect blood test results, pulse ox, and sounds coming from your lungs. Have you had an x-ray?
I have acute asthma and when my anxiety ramps up, I get shortness of breath feeling. I don't think I'm really short of breath because when I'm busy at work, I don't even notice it. It's not until I think about it, do I start breathing that way. I'm one year older than you BTW.
I get the same fears though and last time I had this, those fears were extinguished with a chest x-ray...but even if I get that done, I just roll onto the next disease.