I’m glad I found this topic, I just got to level 6 and started around the same time as you so I would say you are doing great! Congrats for not giving up and going quite fast (in my opinion, at least ^^)
Reading about your worrying first stressed me a bit but the comforting answers you received kind of soothed me, and I will be expecting some sort of high “step” at level 9.
I think for this kind of learning, the most important part is to acknowledge you know more every day even though you don’t see it. Nothing is “useless” here, we are always learning or getting better at what we already learned.
がんばりましょう!