I took a look at your WaniKani profile and your Apprentice and Guru counts both look pretty good.
Are you seeing similar number of reviews every day? Or do you have some days with barely any reviews and other days with a ton of reviews? If you do all/most of your lessons right when you level up you’ll get those weird spikes, so if you’re seeing that it’s best to spread out your lessons (with something like [Userscript] WaniKani Lesson Filter if you want). Of course, I’m just guessing, and maybe you’re already doing this.
Other than that, if you do fewer lessons you’ll get fewer reviews, so you can slow down. You’ll level up more slowly, but this should reduce your daily workload as well.
Of course there’s leeches as well, but since your Apprentice and Guru counts look fine, I’m not sure if that’s a big issue right now. You can check your leech counts with something like [Userscript] WaniKani Dashboard SRS and Leech Breakdown. If it turns out you do have a lot of leeches, you can give them extra attention with [Userscript] Self-Study Quiz and [Userscript] Additional Filters. But again, whether that’s needed depends on how much leeches are impacting you. And of course this could actually add to your workload (extra studying for leeches) until you start to get a hang of them, at which point you’ll have fewer reviews and should save time.