What is the religious ruling on a girl who reached puberty and did not break her fast in Ramadan due to menstruation, out of shyness and ignorance, and did not inform her parents, and now feels anxious about it?

You must repent and seek much forgiveness, and make up the days of Ramadan that you missed in the year you reached puberty and began menstruating. You are required to fast a full month in place of the month you missed, excluding your days of excuse.