From your 106" screen, how far is it to your eyeballs while seated on the white sofa? Due to the wide-angle lens, the proportions are off, but it still looks like you might be sitting a little too far away relative to the screen size.
Use this handy calculator:http://myhometheater.homestead.com/v...alculator.html
I'd suggest possibly moving your couch closer and getting some matching side surround, wall mountable speakers and using the bookshelf speakers currently placed in the bookshelf unit as back surround speakers. The left side surround would be placed on the wall next to your double doors. Adjust your shelving so both back speakers are at the same height. You then have a full 7.1 setup. Be sure to rewire your receiver so that the current back speakers are actually now seen as used for the back surround channels.
If you only have easy access through the ceiling for wiring the side surrounds (and not the side walls so you can fish them through from the attic), pull the wires down through small holes in the ceiling and crown molding right next to the wall and hide the hanging wires behind paintable, plastic wire molding down to the side surround speaker locations. That's what my neighbor did when he re-worked his bonus room and it looks just fine.
As for the screen wall, I would move your equipment to a normal equipment shelf rack and place the center speaker on a proper speaker stand. It would lessen the equipment clutter and you could set your center speaker below the screen in the center of the image where it should be.
Look into some non-permanent acoustic wall (ceiling too?) paneling and corner bass traps. They can be fairly aesthetically pleasing and will greatly improve the sound in your room.
Too bad you can't change the room colors because they're really too light for a projector and screen. Dark colors and a black ceiling are ideal.
I would make one equipment upgrade suggestion: replace your Polk subwoofer with an HSU VTF-3 mk 4 or VTF-15h. You'll thank me later.