Can I ask what the angle between you and your speakers is? Or, easier to measure, the distance between the 2 speakers and the distance between each speaker and your ears.
Also, I've just noticed something. The wall oposite your sofa slopes. I guess it's a top floor flat. I don't know if this is a good or bad feature, or what could be done to reduce its impact if it's an undesirable feature. Others may have a view on this.
I must say, I'd like to see horn speakers (used Avantgarde Unos perhaps) that could be placed close to the wall and less likely to be upset by the room's features.
The speakers and listening position are close to being in an equilateral triangle - but I may adjust this. The speakers are around 3 meters apart, and my seating position around 2.8 meters from either speaker. In the pictures, the speakers are wider apart.
Funny you mention the slopes on the wall, as I was just thinking about this. There are also alcoves in the wall facing the couch (one can be seen in the picture).
Is perfect symmetry desirable ? I don't know - perhaps some asymmetry acts like "diffusion" ? Also, I could place in the alcoves some more "absorbant" furniture than what I have now.
The room lacks symmetry, which is a nice feature, from a design standpoint, but perhaps not ideal for acoustics ? I would be curious to see what the effect of adding a screen to the right of the right speaker (and to the right of the couch to block the entrance). This would make the space smaller, so I am not sure that would be desireable, but I am always curious to test things (in a "leave no stone unturned" approach!).