She reached menstruation at the age of nine, and did not fast Ramadan out of ignorance

Question:
May Allah reward you with good. The questioner, Umm Hudhayfah al-Jubayl, sent this question saying: We are a group of girls who started menstruating at ages that did not exceed nine years. Out of our ignorance, we did not fast some months of Ramadan. When we learned of the obligation to fast, we began fasting. What is the obligation regarding making up these days of the blessed month of fasting? Regarding these months, along with giving charity? May Allah reward you with good.

Answer:
It is obligatory for you to fast the days on which you broke your fast. After menstruation occurred, because the one who menstruates has reached puberty, and the religious obligations of fasting, prayer, and others become obligatory upon her. This is based on the saying of the Messenger (peace and blessings be upon him) , and the meaning is the one who has reached the age of menstruation. What you left of fasting Ramadan during the period that passed at the beginning of your puberty, this was due to ignorance or negligence. So it is obligatory for you to repent to Allah (Glorified and Exalted is He), make up the number of days you did not fast, and feed a poor person for each day for the delay. This is an expiation for delaying the make-up until this time. The conscience is not cleared except by this: repentance to Allah (Mighty and Majestic), making up the full days on which fasting was broken after puberty, and feeding a poor person for each day as an expiation for the delay until this time. And success is from Allah.