Morning after pill... how reliable?

So, I had sex about four days ago now (unprotected). Yes. I know it was stupid but it happens. I took the morning after pill yesterday and went to my GP who prescribed it to me but I keep reading stuff online which freaks me out, I just need some closure and also my GP was so blunt like he was saying that the chances are pretty high, however he didn't cum and online it says that EC is pretty reliable so anyone had the same experience because I don't want to get pregnant!!!