Looking how you have the room setup with the tv in the corner, I don't think you have enough room to add a center in that configuration. The left/right mains would need to be wider if you incorporate a center. If you rotate everything including the furniture clockwise a bit, you could make use of that longer wall, spread out the mains, and then have enough seperation to add a center.
In addition, I'm not sure if you were trying to simulate a surround environment by aiming your 22's the way you have them, but you would be better off moving them to the left and right of the seating area closer to the walls and aiming them towards the seats. That way the surround affects would be proper for 5.1 channel.
Also, if you rotated the room clockwise a bit, you could use the 22's for rear channel, get some Qs8s for the side surrounds, and get a center. $$$$$$$$
