If your system photo is current, just try toeing them so that the axis of the speaker crosses just in front of your listening position. That will help eliminate most of the sidewall reflection issues, and potentially improve ceiling reflection/dispersion issues. It could also let you move your speakers closer to the side wall. Worked very well for me in a 13x19.5 ft room where my speakers' centers are about 2 ft from the side walls, 6 feet into the room, and a listening position about 4.5 feet from the back wall.
If this doesn't do the trick, moving your chair over to the right 6" or so might do it too. Or a combo of both.
