What Causes Delayed Period And Brown Vaginal Bleeding After Taking Postinor-2?

Hi, I had sex wif my ex, took postinor the next day,(within 24hrs), had sex again the day after, took another set of postinor 2. One week later, I get brown vaginal bleeding,lasts for 3days(little amount). Its been almost 2weeks now. I haven t seen my period since. Am I pregnant?