Is what the questioner does—not bathing until the fourteenth or fifteenth day when she sees nothing—correct, and does Ibn Abbas's statement apply to her, knowing that her habitual period is seven days, and what follows is yellowish and brownish discharge that sometimes extends to the thirteenth day?

If a woman sees yellowish or brownish discharge during her customary period, or if it is connected to blood, it is considered menstruation. However, after purification (ṭuhūr), it is not considered anything, based on the statement of Umm 'Atiyyah: "We did not consider the yellowish or brownish discharge after purification to be anything." So, if the blood and any connected yellowish or brownish discharge cease, ghusl (ritual bath) becomes obligatory. If the yellowish or brownish discharge reappears after that, it is not considered menstruation. The prayers that were missed after the cessation of menstruation and before performing ghusl should be made up.