Discover your own rhythm
Print the Moon Calendar of this year and record it in it. The first day of your period, the days of duration, the volume, moods, or any annotation that you consider important during the months.
Don't limit yourself to the days you have your period.
You can also record if you have colic or uterine cramps, the days you are ovulating, if you feel any of your ovaries, how you feel on those days.
And at the end of the year, see what your rhythm is.