I would stack the entire corners with rockwool, from ground to ceiling, to deal with the build up of sub frequencies.
And maybe sit closer to the front (or back) wall to prevent standing waves messing up your bass response.
http://arqen.com/acoustics-101/speaker-placement-boundary-interference/

 

ASC attack-wall the best

https://www.rspeaudio.com/Attack-Wall-Webboutique-a/276.htm

http://www.asc-studio-acoustics.com/products/attack-wall/

 

Yes, I've decided to stack the corners with rockwool and I'm currently updating the design. But I have to measure the room properly first.

 

That look so cool and expensive! But I don't think I'll be able to afford one.

 

I did teh same bro I t took decades that I finally have a good thtreated room. First egg cartons at teenage years than foam , that high density corner traps as foam and finally proper traps after finally having a bigger room. I think I payed around 1700 Euro alone for teh materials :D I took some time to understand how all stuff woks together but it is worth it.

Ive choosen agains rockwool since I also sleep in that room and I dont trust air sealed stuff :D
Maybe to much paranoia but that can get annoying when tripin' :D

 

It must feel so good! Guess I'll have to find a way for me too, and I realized spending too much on my current room is not a good idea.
I decided to make a bunch of 6 inch thick panels straddled across the corners, floor to ceiling as bass traps. I guess that'll do for now.