Is the 'Umrah valid if a woman circumambulated the Kaaba while she was menstruating, then became pure and performed the 'Isha prayer after the circumambulation, bearing in mind that pinkish water was discharged from her the following day?

Your 'Umrah is valid, and there is nothing against you. What descended after the emission of the white discharge is not menstrual blood. There is nothing against you concerning the circumambulation (Tawaf) and praying its two Rak'ahs before the 'Isha prayer, as long as its time has not expired. Even if the time had expired, it would still be permissible if you had forgotten.