I Started Taking Postinor 2 About 3 Weeks Ago But

I started taking postinor 2 about 3 weeks ago but I forget to take it the last time I had s*x which I had 72hrs to take it but I did not I was so busy I forget... But I know that the side effects is bleeding tiredness etc. Since I started taking it I got a bit of blood up to this day even though I didn't take it but my periods is late could I be pregnant or my cycle just change