If you can post a photo or two that will help. Better, measure your room using appropriate software and post the results. Here are my standard measuring suggestions:
ETF, Windows, $150 FuzzMeasure, Mac, $150 Room EQ Wizard, Windows and Linux, Freeware Using ETF explains how I use ETF, but the principles apply to all such programs.
Comparison of Ten Measuring Microphones
--Ethan