Just a quick update, in case anyone’s interested:
After getting an accuracy betweend 65-83% (more in the 60s most of the time) for the last three weeks, I am now finally at a ~90% accuracy again. Today’s score:
The days after my “0 reviews” were actually especially hard, I still had around 300 reviews every day and on some days I got around to only 100 max. And the low accuracy made it kinda frustrating. BUT I feel I’ve gotten to a turnpoint. The last 3 days I had around 170 reviews every day, which is really manageable.
The hardest part for me right now are the vocabulary words which I had problems with even before the short break. All the combinations with 想 (concept) are especially hard, since I don’t seem to be able to remember the differences between most of them. Especially the ones with plan vs. anticipation. T_T
But well, I guess I’m gonna have to find a strategy for that. If anyone has any good mnemonics or something else, please share!
One other thing I had problems with, 仲良く, isn’t a problem anymore, since thanks to @gojarappe and @nbeck0212 I am reading picture books now and all the animals are always 仲良く遊び-ing with each other. To keep myself motivated those books are pure gold!!! They are easy to understand, cute and if you look for the titles on You Tube you sometimes find someone reading them out loud. I have finally also started with a textbook again, “Japanisch Schritt für Schritt”. It’s very easy and beginner level, but right now that’s better for my motivation then trying something more complex.
So, I’m looking forward to the rest of my journey. I hope no more long breaks are ahead of me, but even if they are, I feel more confident than ever that I WILL someday be able to speak and read japanese on a level I’m happy with. 
Oh, and I even did 6 new lessons on WK yesterday!!! It felt soooo good to finally learn something new again and to make the number of lessons a bit smaller. 