Thank you for your replies. They are quite helpful to me as I am on a steep learning curve since I found out I had sleep apnea and low saturated oxygen levels (which apparently have not improved even though my AHI is usually in the 1 to 2 range with auto CPAP).
My doctors also told me that my tuba playing should have helped make my lungs stronger (I did a lot, quite loud, over the years from around 1951 through 1978) and then I tapered off.
I have tried to lie on my side but I always go back to lying on my back while sleeping. I try to prop one side up using a pillow so I am at an angle and that seems to work somewhat. I must keep my feet elevated while sleeping ever since they started turning blue / purple back in March (my regular doctor and podiatrist ran tests and don't know why). I wonder if my blue feet have something to do with low blood oxygen. My elevated feet make it more difficult to lie on my side, I think.
Anyway, update on the oxygen assist: I still have no oxygen system. I contacted one of the sleep nurses Tuesday and she thanked me for calling it to her attention (I guess they didn't know that nothing had happened since they submitted the order a week ago). She said I will soon hear from the home health supply people soon (whatever "soon" means). I won't hold my breath.
Thank you again for sharing your experiences with me. They help me to understand what is going on!