What should I do now, is my fast valid, and is intercourse permissible now, knowing that I gave birth more than two months ago, and the postpartum bleeding (nifas) only stopped after a procedure to remove a piece of the placenta in the first week of Ramadan?

The maximum duration for post-natal bleeding (nifas) is forty days. After this period, the woman is considered pure and should pray, fast, and her husband may approach her. Any blood discharged after the forty days is considered a hemorrhage, not nifas. Your fasting after the surgery is valid, even if blood was discharged. You must make up for the first week of Ramadan that you did not fast. You are not required to make up for the prayers you missed after the forty-day period.