The i-Pill (levonorgestrel) is an emergency contraceptive medicine and works only when taken shortly after unprotected intercourse, ideally within 72 hours. It will not be effective for intercourse that happened several weeks ago, and it cannot start a period or end an existing pregnancy. Since your last period began on 4 April and you have not had your next period by 12 May, pregnancy is a possibility, even though intercourse happened on the last day of your period. The most appropriate step now is to take a home urine pregnancy test, preferably using the first morning urine for better accuracy. If the result is positive, you should consult a doctor for further advice and care. If it is negative but your period still does not come within a week, repeat the test and seek medical review. Stress, hormonal changes, or illness can also delay periods.