Thanks a lot for your assistance! It is a bit late to fill the room with sweep tones right now where I live. I will attempt tomorrow.
Reflections make sharper dips and peaks. Small rooms like yours are very difficult!
Looks like you used REW default 500ms gating, it picks all reflections and modes.
Panels look huge and they don't need to go to the floor.
Lift speakers off from table and put them closer to the front wall!
https://www.genelec.com/monitor-placement
https://www.thomann.de/blog/en/8-tips-get-best-studio-monitors/
https://www.soundonsound.com/acoustics-studio-design?f[0]=node%3Afield_section:6971
Take some time, search internet for advice on desktop monitor installation.
Do more measurement with different speaker position and mic position
Do tests with panels, measure separately for L and R speaker.
MMM measurement of some kind is better to imitate the sound that you hear. Recommended!
I am not aware of the 500ms gating, but I must have used the default setting so it is probably that. If that is the case then it will be peaking up modes for sure. In fact, the measurement contained waterfall information, I am not sure if that is what you meant, but it definitely showed even longer times in the waterfall plot . (It was meant to be a room measurement, not a speaker one).
As for the panels, they are not huge really, it is the standard most used size, as it fits the most common size of the insulation boards in the market (0.6x1.2m - or 2'/4' in other words). I know they don't need to go to the floor of course, it's just that they need to be placed this way, since they are not attached to the walls ;-) . I would have placed them horizontally if I could of course, though to be honest the insulation I used is meant to perform well for a panel absorber even in the lower mid area (coefficient is measured at 0,35 @125Hz in a 1/3 octave measurement), this is way I use it in the SBIR panel against the front wall also. Regarding the "closer to the wall" speaker placement, I haven't checked your links yet, but I know many suggest doing so, so that the SBIR low frequency is pushed upwards so that it can be treated more easily, if that is your point. The problem is that if I do so, there will be some desk reflecting surface area in front of the speaker that will interfere with the direct sound, quite likely creating comb filtering issues. Also, in this current setup, the sound is less "stiff" if you will, plus the SBIR panel needs to be a bit larger to cover the whole area behind the speakers - which I am planning to do in the near future - meaning it currently doesn't work the best way it could...
Anyway, I can definitely take more measurements with different mic placements as you suggest, but I am afraid I can't experiment with speaker placement since it is a really small room as you can see.
Separate L/R measurements are also possible. Will do!
Thanks!