I applaud your efforts. That's outstanding.
I like your decision to use glass wool; it's so much more effective than foam, especially on the bass frequencies.
If I can make a few comments:
You may want to experiment with the mic position. Even soft material reflects a certain amount of sound, so having it very close to the booth wall is going to pick up quite strong reflections in to the back of the mic. You also have that wooden upright support very close to the mic which is going to reflect sound. See if moving the mic forward 20-30cm makes any difference. If you do that, you may also need to experiment with the tablet position (reflections, again).
The other area to consider treating is behind you - that's the direction the mic's pointing so that's obviously where any residual echo will be picked up. A blanket hanging close to your back is often effective. Also, if you have the space to turn the booth so that your back is facing a corner of the room rather than being square to the wall. That often sounds better because it's harder for echoes to be reflected from room corners.
Happy experimenting, and thanks for sharing your hard work.
Everything except LibriVox (yes, this is where knitting gets discussed. Now includes non-LV Volunteers Wanted projects)