One feature in Monthly Rose that's been worth building: it turns what you've logged (period dates, symptoms, mood) into a single page you can show a doctor, instead of scrolling through months of calendar on your phone in the exam room.
It's on iPhone and Android. 7-day free trial, then $5.99/month for Basic.
App Store: https://apps.apple.com/us/app/monthly-rose-period-tracker/id6816627178
Google Play: https://play.google.com/store/apps/details?id=cn.iyunci.yueji.gp