Graded readers aren’t typically arranged by N levels. It’s more an “easy to read” text that is designed to foster reading capability. Generally they are children’s books or collections of easy to read folk tales that introduce you to the concept of reading in your target language.
The ones I was recommending specifically are Kodansha Kanji Learner’s Course Graded Readers. The problem you have with these is that they follow the Kodansha Kanji Learner’s Course, not the WaniKani order of kanji learning. KKLC uses frequency of kanji instead of WK taking radicals and grouping kanji according to those radicals.
I would recommend, once you decide to move on reading, check out Resources for Starting to Read Japanese Content. Scroll down to the graded reader section and see if any of what is there makes sense to check out.
In my mind, even if you can’t understand what you are reading, attempting to read it allows you to practice the characters you do know. Once you start getting grammar down, go back to the graded readers to get kanji recognition AND grammar practice. Eventually those will be too easy but until they are, they are hard enough to make them a goal in my opinion.
Sorry if I am rambling here. I hope this helps and if there is anything more you want clarification on, I will try to be more clear.
Hope this helps you!
And… don’t give up!