If one of your discomfort issues is feeling suffocated then that 5 cm starting point is a very likely culprit.
I did a screening of my own sister with my APAP machine and I wanted to use 4 cm because all I wanted was to see if some events popped up and she couldn't tolerate either 4 or 5 cm...she said I was trying to kill her by suffocating her.
It wasn't until I tried 6 cm that she could breathe comfortably.
If you aren't comfortable making a small change in pressure yourself then get with your machine supplier Monday and tell them that you are having problems breathing...feeling suffocated.
Also if your mask is too tight...it actually defeats the purpose because they need to inflate to work properly.
So besides it hurting like the devil if the mask can't inflate properly then the air doesn't move well and compound it with a low setting and it is uncomfortable.
So if you can describe each problem you have so that we have a real good idea what you are going through then we can come up with ideas to help.
Success to me is also an improvement in quality of my sleep and how I feel each day.
The cpap part of my therapy is a success. I no longer wake up with killer headaches from oxygen level drops to the low 70s. I no longer have to get up to pee every hour on the hour. I no longer nod off to nap at 9 AM when I just got up at 7 AM. Do I feel like running a marathon? No, I don't but I am 60 years old and I have other health issues and arthritis and I wouldn't feel like running a marathon even if I didn't have sleep apnea but you know what....at least I don't wake up every day feeling like I have just run a marathon.
The machine fixes one thing...sleep apnea...it doesn't fix stuff that is unrelated to sleep apnea. If we have poor sleepy hygiene or have insomnia or we only get 4 hours of sleep or the meds we take make us groggy during the day or whatever....it doesn't fix "bad sleep" and bad sleep can come from a whole lot of other things. There are a lot of sleep disorders besides sleep apnea.
I think a lot of "failures" come from people expecting the machine to fix something that is unrelated to sleep apnea.