Is the front of your working desk a solid flat surface? Obviously the chair to the left of your desk has a solid back. It seems to me that you're sitting behind a wall, OK a half wall. I'm thinking that the bass is bouncing off those flat surfaces as well as being absorbed. And to add to the perceived lack of bass the highs are bouncing off the top of your desk right into your ears.
Although I can see where this would be a PITA I would move the desk and the chair out of the room as an experiment to see how much they are affecting your system.
I had a coffee table in front of my listening position and I was quite surprised that removing it mellowed out the highs considerably. It never made it back into the listening room.
Regards,
barts