How can a woman with an irregular menstrual cycle, who experiences discharge of varying colors, determine the times for prayer and fasting, especially with the approach of Ramadan? And what is best for her to regularly observe among the supererogatory fasts (Mondays and Thursdays and the White Days), knowing that fatigue sometimes affects her ability to fast? And is she sinful for breaking her fast due to extreme fatigue resulting from worldly matters?

Your duty, when the bleeding stops, is to pray and fast. During that period, all rulings applicable to pure women apply to you, even if it is prolonged. If the bleeding duration exceeds fifteen days, it becomes clear that you are experiencing istihadah (non-menstrual vaginal bleeding). Your consistency in fasting on Mondays and Thursdays and the White Days is a good deed for which you will be rewarded. There is no blame upon you if you break your fast on those days due to a need, as they are supererogatory, not obligatory. It may appear that being consistent in fasting on Mondays and Thursdays is better, due to the abundance of deeds performed therein.