How fast did your COPD progress?

I know everyone is different but I would like to know how fast did your COPD progress to the point of using O2 24/7. I am considered stage III emphysema with FEV1 46%. I have probably had it for 10 years plus. Quit smoking 10 yrs ago. But this last year went kind of downhill from stage II to III and put on 02 for exertion (which means once I start moving around) and night. I find myself really struggling more with shortness of breath & energy levels. I completed rehab and following up with exercise & walking 30 min a day. I know this is a progressive disease and would like to hear your experience. Thanks Diane