When Do Periods Start After Taking I Pill?

I had unprotected sex with my fiance so i took ipill immediately. Now i experienced an unexpected light vaginal bleeding for two days after 10 days i.e 10th jan and 11th jan 2015 of taking ipill and 15days after my regular periods. so should this spots be considered as my regular periods? plz help last month i had my periods on 27th dec 2014.