Hellodmahabir123. Thank you for posting today.
A common side effects of ECP (emergency contraception) is a delayed next period. So, you will have to wait for your cycle to sort itself out. You had a withdrawal bleed and a negative pregnancy test so this should ease your mind. You can always test again in a week or two if you are still unsure. For future, it's best to use protection no matter what time of the month. It's less stressful will not interfere with your menstrual cycle.