Cathedral Ceiling the Culprit in New Music Room?

Here is me issue. New place - new music room. Dimensions: 22 X 15 with a “cathedral” ceiling running the long way beginning at 8’ and rising to 11.5 feet at the apex. A 4X6” beam running widthwise every four feet.
I am forced to place speakers on one of the long walls. The front wall has two small windows w/horizontal shades at a height above the speakers and components. The rear wall has 15 feet of sliding glass doors and a glass panel which are covered by floor-length drapes. Left side wall is without windows. The right side wall is also without windows but has a 4’ x 7’ opening which enters into a 4’W X 13’L X 8’H hallway, terminating in a door.

I have some book and record shelving along both side walls. I have DIY Jon Risch-design, w/plastic film, 4’ X 16” bass traps in each of four corners (with the rear/right trap in the opening where a corner would otherwise be). Speakers are 60” out from the front wall and 78” out from the side walls. Listening position is centered between the speakers and against the back wall.

With the same components in my previous house (room 19X17) I had very lively, very coherent, very expansive sound. In this room the sound seems rather “dead” by comparison with thumpy and diffuse bass response, bordering and straying into boomy. I am assuming this is mostly due to the ceiling type and I am hoping that this makes sense and that someone has suggestions regarding this issue. I understand that it is hard to make constructive comments without “being there”, but I am even at a loss as to what to try for starters….