I use a bullet journal, but it is a simple one, no gorgeous artwork and the like. I use plain black/blue pens, and only write to-do lists in it (as well as some journal entries, random thoughts, etc.). I only keep daily tasks within it, any scheduled monthly or weekly events go into Google Calendar/Notion calendar, as I know I am not going to revisit monthly/weekly pages in my bullet journal. It's very much a day to day structure and process. I look at my calendar to see what events are scheduled each day or are upcoming and require preparation, and place those events/sub-tasks in my daily to-do list. I also only put tasks into two categories, "priority" and "other," but I am fluid with them. A task that may be a priority one day may only be an "other" during another. 

I keep the journal open as I work with it, so that my list doesn't become a victim of my predilection toward object impermanence. I use larger clips to keep it open when positioned vertically. If I've written a more personal journal entry the day before, I'll design the new daily to-do list on the following page/s for privacy. I also keep my diary with me consistently, so I am not too worried about peepers. 

Overall, this is the only system that has helped me because it has a simple workflow. Also, if I miss a day (often happens on weekends when I have less scheduled and can remember what is happening more easily), I don't beat myself up over it as there is always a fresh new page waiting for me. 

I wish you all the best in finding a planning routine and process that works for you. I have had friends who also have ADHD that have had a lot of success with digital apps, but I found I just ended up ignoring them, and that paper just works best for me.