I would not be too concerned for below 100 Hz at the moment anymore - even though a bit shorter could be nice. The higher frequencies are showing much more elevated reverb in relation. I would add some panels behind the couch at the early reflection points to try to get below 0.4s. This should benefit your sound state quite a bit.
For the measurements, stick to the 90 degree orientation to the ceiling, as was indicated before, or your estimates will be quite off. Curious to see your next steps.
It was mentioned before but be careful with wrapping the rock/stonewool. Cloth might let some fibers escape and it can become very irritating to your respiratory system over time. I would always use plastic around them and have porous panels for the higher frequencies.
For the measurements, stick to the 90 degree orientation to the ceiling, as was indicated before, or your estimates will be quite off. Curious to see your next steps.
It was mentioned before but be careful with wrapping the rock/stonewool. Cloth might let some fibers escape and it can become very irritating to your respiratory system over time. I would always use plastic around them and have porous panels for the higher frequencies.