I did struggle and came to the same conclusion you did. Writing down the items with their meanings and readings was definitely a game changer, it really helped me make a significant jump with dealing with new kanji outside of wanikani. I try not to learn more than 5 new kanji and even less when it comes to the radicals, so I can space the amount of new materials in a way that doesn’t overwhelms me.
Keeping an eye on the level of my apprentice (trying to keep it between 50 and 70 as much as possible) and trying not to go overboard with the number of lessons per day has also helped, it means not doing new lessons some days, which is fine. And always backing it all up with grammar and graded readers and now with gaming.
It took me some time to create real familiarity with the writing system, there’s only so much you can deal with when it’s all new and there’s nothing familiar that you can build the new information upon. Reading is important because it gives you some real feedback where you are not being tested, you just doing stuff at your own pace, and when you read material that is suitable for your level it’s an excellent positive reinforcement of everything you’ve learned.
You can read about people’s journey while it happens in the study logs section you’ll be able to find all kind of approaches see if anything speaks to you.
You can also see some examples of how to deal with leeches and mnemonics that don’t work for you on this thread Confusing Mnemonics and Leeches Help Thread