Does your machine allow you to slowly ramp up to a moderate pressure? It took me a while to get past feeling that I could not exhale properly once the machine was on. Your machine may have an autoset feature or a an extended ramp up time, either of which reduces the feeling of being "invaded" by the gust of air when you turn the machine on. I do agree that it is not easy to get used to feeling like Darth Vader, and I sometimes take my mask off after 7 hours and grab a more comfortable hour without it. However, there is a big difference between some discomfort and feeling that you are struggling. Does your DME provider have anyone who can work with you?
I have been using a ResMed with nasal mask for about 40 days now. You did not say whether you use a chin strap or not, but FYI, I tightened the chin strap to try and keep my mouth closed better, and the increased pressure on one of my lower teeth loosened it enough to feel it move and see a little blood emerge. If you do not have a good bite or your jaw recedes, it is possible to irritate your teeth. If you have a good dentist, you might want to take your headgear in and let her/him look at what is happening with your jaw and teeth while you are geared up for the night.
