Hello, Thanks for the query. I understand that you need to delay your periods and want to avoid it on 11th and 12th . Taking into consideration your normal menstrual cycle, it is highly expected that without external intervention ,you may have your periods on 11th and 12th. Had i been your consulting Gynaecologist, I would have prescribed you Primolut N(Norethisterone) . Now this medicine is taken thrice daily , starting three days before the expected onset of menstruation and continuing for not longer than 10-14 days. So, since your last periods were on 19th feb, you may start with thrice daily dose of Primolut N from 10th feb and continue it for not more than 10-14 days or whenever you want to have your periods, whichever is earlier. A normal period will occur 2-3 days after you stop taking the pills. Here, you havent mentioned whether you are married or single. I am mentioning this as this method of delaying menstruatuon is restricted to users who are at risk of pregnancy during the treatment cycle. Also , you should avoid this tablet in case : 1. you are ensitive to Norethisterone 2. Known or suspected pregancy 3.Lactation 4.Recent or active thromboembolic disease eg: history of angina or myocardial infarction 5. History of migraine with any neurological symptoms 6.Presence of diabetes with vascular involvement. 7.Any liver derangement 8.Breast cancer 9.Undiagnosed genital bleed So Consult your gynaecologist to alleniate any of these conditions .