I would go for nasal pillow and not mask , as it looks like the nasal mask is just a smaller FF mask. It doesn't take a lot of getting used to and I have even in this short time jumped and purchased the Resmed Swift LT nasal pillow and its so much better than the Swift II (I got from the hospital) as it allows very comfortable side and front lying positions. Got it direct from Resmed UK (
http://www.resmed.co.uk). Join their sleepVantage and you get a discount (down from I think 105 to 79 pounds). I also brought humidifier H4i as I could see I was in for a dry nose.
So everything now comfortable. But my early experience of keeping my mouth closed hasn't actually panned out. I think because my brain is nuts and wants to learn what its doesn't feel natural to do, also leaks do the same in that the pressure ramps up. Seems for me the effect of this is I swallow air and get bloated (called aerophagia). So plan of attack is , I have ordered a chin strap to keep my lips closed so I don't have to worry and I may drop the max pressure as stats say I have only bee to max about 12.5. So leaks blowing to 19 is pointless. The other thing is nasal pillows come with 3 nostril size fittings which is good. I am trying medium that's leaking occasionally. Tried the small which seals brilliantly but seems less air gets through. So going to go to small and up the min start pressure from 4 to about 6. I will only bring max pressure down if small fails.
Seems there is a lot of trial and error.
Oh thoughts, your mask problem. One thing I did is follow the Resmed guide (not the quick start) to the letter and this produced a better fit than at the hospital. Especially understanding that you first set top dial to furthest out from forehead. Then put top strap on and tighten. Then put mask over nose and mouth. Should seal even here enough for low pressure. So fit all clips. Then run test fit pressure and bring dial in until it doesn't leak around nose. This dial is key to stopping leaks around the chin and getting the mask to be parallel with you face so the air cushion blows out properly. You should definitley not have anything touching the bridge of your nose. Also whilst on Resmed site get their fitting templates. Make sure you print at the correct size (I didn't at first) and actually check you have the right size mask as I think NHS have lots of medium. I know I really should have had small.
Hope these ramblings help.