I track some of my habits, and I have an illness which symptoms show up between 1 month and a year frequency and I used to forgot when it was the last time. I also track my shaving habits, but it's not as frequent as OP:)

I use Loop Habit Tracker, it's foss and on fdroid:

• https://github.com/iSoron/uhabits
• https://f-droid.org/app/org.isoron.uhabits

Some years ago I tracked my weight, but it was too depressing, so I stopped. There is also a good foss app for that, Waistline: https://f-droid.org/packages/com.waist.line/