Hi I Am On My Period And I Had Somehow

Hi i am on my period and i had somehow unprotected sex...i took postinor 2 after about 30minutes and took the next one after 12hours. This evening i saw some blood. I mean i already am on my perios but it didnt come the whole day until this evening and im wonderin could be the effect of the pill? And i'm i a 100% guaranteed am not pregnant? I have some abdominal pains though.
Thanks.