Hi. Thanks for asking in Healthcare Magic. Noerthisterone is a progesterone. High dose of Progesterone can stop the onset of period. But once the period starts then oral tablets may not be effective. Generally one injection of Medroxy Progesterone Acetate followed by Norethisterone tablets are given to arrest the bleeding. You should continue the tablets as long as needed but not more than 10 days. Withdrawal bleeding will commence within one week of stopping Norethisterone. But since your period has started a week earlier and you are having a light bleeding the tablets may be effective. You can try them and if they are not effective then you can opt for injection. Another alternative is a combination of Mefenamic acid and Tranexamic acid. Your treating Dr will know about theses drugs. Although you can postpone your period by using progesterone, it is not advisable for frequent use and you should not practice it on a regular basis especially if you are yet to start a family. Yes,stress definitely interferes with menstrual cycle. It can either delay or expedite the period. I hope this is useful to you.