I have Idiopathic Pulmonary Fibrosis, but am not yet on oxygen, and also have long standing circulation problems/angina. Despite my age-lined face, I am told that I usually look healthy! Certainly, I 've had baleful looks from bus drivers because I wouldn't hurry, honking from car drivers if slow crossing the road and irritation shown if I have requested a young person to vacate a Priority Seat on a bus, etc.
Then, last year, I developed arthritis in my hip. Not too badly but enough to make me try using a (folding) walking stick. Wow! It must be a Harry Potter model! Suddenly bus drivers wait for me and even delay starting until I am seated; car drivers are patient and may even stop for me when not at a Crossing; I get offers of help if I drop something while shopping; and last week, on a rare visit to London, several people sprang up at once on a couple of tube journeys!
The most surprising, however, was in Bangkok and Chiang Mai airports this Xmas (en route to visit sons in Australia and NZ). As soon as I approached a queue (check-in, immigration and customs) someone sprang forward and ushered me (and dear wife) either to the head or to a fast-track lane! In fact on one occasion they would not take NO for an answer and insisted I be pushed in a wheelchair all the way to the departure gate. My wife was not so pleased as she struggled to keep up! I have to report that no such assistance was offered at Heathrow or Melbourne, alas.
So, if you feel your difficulties are not adequately recognised while out and about, get yourself a walking stick. I can't guarantee it will be a magic one, but I am sure you will get more recognition.