Mask Help

Ok it has been since last November when I started BIPAP auto. Still having mask issues. I'll go for a few nights with a low leak rate and very good AHI rate and then all of a sudden I egt high leak rate and high AHI rate like 16.1. There has to be a mask that fits on a consistent basis. What do you all think of the LIberty. I have never tried nasal pillows but I have a nasal mask (comfort gel) and I have the Quattro, Comfort full 2, and Comfort gel full masks. None of them stay sealed when my pressures get up higher than 16. My original numbers were 20/17. When I get a good seal I rarely go above 16/12. Thanks for any help. I am really trying to do this but can't afford to keep trying masks.