I have had at least 3 Pulmonary Function tests, the most recently in April 2015.  I have never been told what my percentage of lung function is, even though, I have asked.  My question seems to be just brushed off as if the percentage cannot be reliably gauged.  Additionally, I have never been told what stage of COPD I am in.  When first diagnosed, I was told I had moderate-to-severe Emphysema...moderate doesn't seem bad, but severe does.  Is it important for me to have a definite answer?  I am thinking that I am at least stage 3 and 50% or less lung function, since I am on O2 24/7.  Without O2, if I sit quietly my saturation will be about 87/88.  If I move around just a little bit from room-to-room, my saturation drops to about 74.  I would just appreciate some opinions.  I completed 37 Pulmonary Rehab sessions in early July and have started Phase III Pulmonary Rehab, going for the last 3 weeks, 2-3 times a week.