Kathie,
I am currently taking some iron (65 mg daily)... not much, I guess. Also I am taking a Super-B Complex supplement -- it has 250 mg of B12 in it, among other things -- but this is something I just started doing on my own.
I haven't really experienced the "unable to take a deep breath" phenomenon you described. However, in the past (back in 1996) I had some lung issues... I had about a 6 month bout of an "autoimmune" type disease called sarcoidosis, and during this time, I would have coughing fits that seemed to go on forever -- also fevers, aches, swellings in ankles, etc. But this was an "acute" attack apparently, and in a few months it went away never to return. Unless, of course, it is now the cause of my pancytopenia somehow? Unlikely, but... who knows?
I wonder if having low hemoglobin -- or perhaps just knowing that you have low hemoglobin -- can cause that sensation of not being able to get enough oxygen? I just don't know. Maybe someone else on the Forum knows.
Keep in touch!
David M