You will most likely do well with your ultra mirage, any mask takes a little practice to get "just right" . Don't forget you can also change the forehead pads angle, moving it closer to the forhead relieves nose bridge pressure.
If you do decide to look at other masks,
www.resmed.com has videos on their site showing the proper fitting of the Swift nasal pillows...and the Activa nasal mask.....wathcing them will help you decide if either of these masks might be better for you.
As a side/tummy sleeper, I find the breeze nasal pillows is perfect for me, but also like both of the above.