Does it work?

Any effects?

First time taking it i know what it is for. But how does it work. I had sex with my ex and well no condom. I know stupid and wrong. Well we met a half hour later he bought me the pill and i took it. But will i get any cramps?

P.S i got my period friday and today was my last day. I wasn't bleeding only tiny spots when i wiped. I'm not worried because i just ended my period and took the pill i know that makes it less likely for me to be pregnant. Right..?