Can you get your period one week after taking the morning after pill?

there are no fail-prove methods to contraceptions. Although pre-cum may contain only secretion from the Cowper's gland, but there is a chance that there is sperm from previous discharge or small amount of sperm in it. Morning after pill regulates your body hormones to control your ovulation and menstrual cycle, but there is always chances of failure too. Keep watch for a few weeks for any body changes that might signify pregnancy and test with a test-kit.