Is it permissible to perform ritual purification (ṭahārah), prayer (ṣalāh), and marital intimacy (mu‘āsharah) if a woman sees a discharge with blood one or two days before her menstruation is due, and then a white discharge appears, but menstrual blood does not flow?

This discharge is considered menses if it occurs at a time suitable for menstruation. The criterion for the time of menstruation is explained in Fatwa no. 96371.

If you see purity from this blood, then you must perform ghusl and prayer. If the blood returns, you are again considered menstruating.

Your ruling during the intermittent period of purity is the same as that of pure women: you pray, fast, and your husband may have intercourse with you. You have all the rulings of pure women, as explained in Fatwa no. 109807.