I Had An Unprotected Sex 5 Days After My Period

I had an unprotected sex 5 days after my period and I took postinor 2 two days after though I missed the right time frame for the second tablet. I took it some hours after the right time. my ovulation was suppose to come on the 17th of sept but I Neva felt its symptoms. 4 days after I noticed that I was bleeding(not as thick as my normal flow) and the bleeding was for 3 days. could that be an effect of the contraceptive I used or could it be that I'm pregnant?