Is the menstrual period that exceeds 15 days considered menorrhagia, and should the day a spot of blood appeared one or two days before menstruation be counted as part of the menstrual period?

You must calculate a period of fifteen days from the first day you saw blood. If the bleeding does not stop after that, then you are experiencing istiḥāḍah (prolonged vaginal bleeding outside of menstruation). If you are unsure of the exact time you first saw blood, consider it to be at the latest possible time it could have occurred. If the duration of bleeding and purity exceeds 15 days, then act as one who is experiencing istiḥāḍah.