I Took Postinor 2 On Day 9 Of My Menstrual

i took postinor 2 on day 9 of my menstrual cycle but took the 2nd dose 18 hours after the 1st dose instead of the recommended 12 hours. i am currently on day 18 of the cycle and noticed vaginal bleeding. i have also been having unprotected sex from day 11 to day 15. how likely is it that this is a sign of pregnancy or is there other reason for the vaginal bleeding?