If you are a bit adventurous, go on Craigslist and buy a used one with a new mask for like $100. You probably are a Large mask size.
Figure out how to adjust it and try it for a few days. Keep a written record of how you feel. See if it helps. Starting at 6 of whatever the unit is will probably be a good starting point.
The only annoying bit is replacing the masks and headgear - they’re considered prescription medical devices, so you have to exploit a loophole in that they are only covered under the RX requirement when purchased as a set. So, I have to buy a mask on one order, and the headgear on another.
It’s a pain in the ass and I’m more than a little bit peeved that I have to beg for permission for this quality of life improvement.
Amazon won't sell you full mask sets, you have to buy the frame/cushion/headgear/tubing separately and put it together yourself. Usully at a very inflated markup.. recently had to pay $100 for a replacement frame after one of the headgear hooks snapped off of my F10.
Other CPAP companies online won't even talk to you without a prescription on file.