Kythyn, I have to agree with Mike in regard to your room's width. The 48" wide 3-panel Tympanis require a room much wider than 12'. Have you tried putting them on the long wall? They will be okay only 3' in front of that wall (your bass panels are far too close to the side walls now, the two closest facing right at them. Very bad for the sound.), with you sitting 8' from them and 1' from the wall behind you. Worth a try! Also, try an area rug on the floor between the speakers and the listening position. Just getting the panels away from those sliding glass doors behind them should improve things dramatically!
Splitting the two bass panels from the m/t one can work, but that requires very careful placement of all the panels in relation to each other. The x/o frequency between the two is right in the heart of the sound of music, where timing is particularly important. The way yours are pictured is (no offense!) completely wrong. Head over to The Planar Speaker Asylum, where you will find lots of discussion on the placement of planars, including Tympanis.