What is the ruling on previous 'Umrahs that were marred by some issues, and is it necessary to repeat and perform them all in a single trip?

Your first 'Umrah is valid because doubt after an act of worship has no effect. Your second 'Umrah is also valid, and nothing is required of you concerning it. As for your third 'Umrah, it is valid, but you erred by traveling to Makkah without a mahram (unmarriageable kin), so you must repent and seek forgiveness. Regarding your fourth 'Umrah, do not pay attention to any doubt concerning it. Your conscience is clear regarding all these 'Umrahs, and you are not required to repeat them. The questioner is advised to inquire about any issues that arise in her worship at the time they occur, and not to pay attention to doubts and whispers (waswas).