Must I repeat the missed fast of a past day, or my Maghrib and Isha prayers, knowing that I found pink discharge, yellowish discharge, and small traces of blood during the day?

Your fasting on these two days is valid, because the blood you saw is not considered menstruation according to the majority who say that the minimum period of menstruation is one day and one night. And according to the view that there is no minimum limit for menstruation, the occurrence of blood after Maghrib is taken into account. Your Maghrib prayer on the first day is valid, and your intention to fast on the second day is valid. Suspending the breaking of the fast on the presence of an impediment, such as menstruation, does not harm it, because the default is the absence of an impediment.