Hyperventilate! Mirage Activa Nasal Mask

Hello,
I am a recently diagnosed patient and have just set up my machine and I am using a Mirage Activa Nasal Mask. I had trouble the first night of use with exhaling. I tried several settings with both the C-Flex setting on my CPAP machine and the amount of air pressure.

Basically, when I exhale, I seem to get a push back feeling which I attribute to the mask because I changed the pressure delivery from 11 all the way down to 6 (and in between) searching for a comfort zone that would provide the needed pressure, but also allow for a normal exhale.

I feel that my equipment is set up properly, but felt like I was hyperventilating with the mask on. I left the mask on for at least 15 minutes in a variety of settings.

Any advice?