Speaker placement - need some help

I would definately try moveing speakers further apart
aprox 8'apart ,tweeter to tweeter and bring them out a touch more .Out to maybe 6' from back walland go from there.
Adjust as needed.

Your room dimensions are pretty near ideal. However, I would strongly recommend your moving the speakers to be against the short wall. Even if the aesthectics of this do not appeal to you, try it anyway.

For just a rough starting point, I would suggest placing the speaker's center of woofer front approximately 5.5 ft from the back/short wall and the speaker center of woofer fronts should be approximately 3ft from the side walls. Toe-in the speakers directly toward the listening spot. And place your listening chair around 10 ft. from either tweeter.

This alteration should provide a substantial improvement in soundstaging, bass, etc. Not to mention not hearing reflections from the back wall.

The measurements above are general recommendations. Fine tuning speaker placement of 1 or 2 inch increments from that point should provide even better imaging, soundstaging, and bass response.

If bass response is boomy, bring the speakers out another 6 inches or so from the back wall. If bass response seems to have disappeared a bit, move the speakers back 6 inches or so.

-IMO

My first reaction is that your system isn't properly triangulated. I would probably have the speakers out further into the room, say 4&1/2 feet, and the listening position about where you have it give or take 1/2 ft I would think that the speakers should be about 9 feet apart with the listening position 10 feet back. I'd use a Radio Shack meter and a test disc to pin down the best location of the speakers and listening position to get good flat bass response and then fiddle with speaker toe-in to get the best sound stage and imaging.