RE: Need a new mask.
Beware, our machine can not accurately detect and classify events when you are having large leaks. So, when you say you AHI is lower with leaks what you really mean is the machine is not reporting all of the events, so you don't know how high the AHI is in reality. The first priority should always be to get leaks under control - as well as possible - so you know what is really going on.
I use the F10 FFM and have most got it under control at this point. It doesn't leak (much) below a pressure of around 12 to 14 above that it leaked massively for me. I run now around 18 to 19 - sigh, so I have some experience handling (and solving) large leaks with a FFM.
First, I completely agree it is easiest to just tighten down the hatches and try to weather the storm, but that doesn't really work too well with the F10, for the reasons you mentioned. Two things I have done that help. First is use the Mask Fit Test, it is your friend. Find the least tight adjustment that will work at your pressure. The seal of the F10 works when the silicone "ballon" along the edge is inflated, not when it is fully collapsed by being over tighten. The natural instinct is to tighten more when you have leak. That should instead be the last resort. Also, the angle of the F10 on your face controls where the pressure points are - always tight the lower straps first to rock the mask away from the bridge of your nose, then if necessary slightly tighten the upper straps. Do it very slowly over days - 1/8 to 1/4 inch of strap at a time and try hard to keep the adjustment even around so the mask is not tilted too far in any direction. And lastly, the mask will train you over time to sleep in positions where it doesn't leak.
Second, try using the cloth mask liners (there are gel liners, but they are EXPENSIVE and I have not tried them). The liners don't so much stop the leaks, they more like smooth them out so the leak rate grows slowly and doesn't just spike up when you roll over. Since the FF10 seal doesn't always recover once it blows out, if you stop the big leaks from a bump you can avoid some of the leaks altogether, since the balloon seal will deform to compensate for the mask shifting position - but only if the mask is floating, if it is tighten down to the point of collapsing, then the seal no longer works. The liners also greatly reduce the noise the mask makes while leaking so you get more uninterrupted sleep.
A combination of those two (and I have mostly stopped using the liners now) over a period of several months of focusing on it, and I now have the F10 floating (slightly) on it's silicone seals at a pressure of 19 and only get a red face maybe once every couple weeks - and that is usually when I failed to wash my face to get the oils off.
It isn't easy, but it can be done, Like I said, I would have nights with 90% of the time I was in major leak when I was running at 13 or 14, but now with a lot of work, and patience I have got it to work up to 19 with few major leaks and my AHI is now down to around 2.5 regularly and occasionally below 1.
BTW, I flop around a LOT in my sleep, I sleep every way possible except on my stomach. So, I can sympathize with your side sleeping knocking the F10 around. Second I also have a P10, and have tried and tried to get it to work, but I am a serous mouth breather and have found nothing that can stop it. It also causes me to swallow air, which when enough is swallowed causes a day of serious abdominal discomfort. If you can stop the mouth breathing (some can) and not swallow air, I highly recommend the P10. It is worth trying to get it to work.
I am not a Medical professional and I don't play one on the internet.
Started CPAP Therapy April 5, 2016
I'd Rather Be Sleeping