Lots of bass at walls, lack of bass in center of room/listening position

I had an issue with my room few years ago, bass was not filling up around my sitting area. Tried many ways to get them filled up by moving sitting position, speaker placement and I was even contemplating of getting a sub in. After I was introduced by Micahel Green with his Room Tune pillows and consulting him I did some placements of his room tune pillows in my room and finally presto bass is now more around my sitting position. Eventhough I'm not getting super low notes as I'm using bookshelf speakers but it was night and day improvement for me. 

Hey just made a discovery.

Just played around with the roon dsp, i hit invert on my left channel, and all of a sudden the bass came out of nowhere, was focused, intense and powerful and evenly distributed as I lean left and right. When you turn invert off on the left it weakens and becomes much more diffuse. So maybe i have something wired incorrectly? Only thing is if i leave invert on, i sometimes get some popping and crackling so sounds on the inverted channel.

Actually this seems to collapse my sound stage and squash imaging towards the center as well

i’ve had the EXACT same issue w huge dip at 80-100hz by mandated listening position. completely solved w a smaller driver(very fast) sub. The b&w db1 is a true system changer. it will play at 80-90hz without any detection issues. i place it just inside left speaker. it has several phase choices which are very easy to hear allowing perfect match w mains. in my room 270 degrees is the correct setting for me. neither 0 or 180 worked well. try it as you will be overwhelmed at the seamless integration.