Pragnency doubt, doctor please read all.

As we had sex on januwary 1st and we did by using condom .and at that time i was in my 6th day of periods .but only for one time i get fucked without condom but his sperm did not enter or i can say that at that time his sperm is not coming .but for doubt after 15 days passed i checked or done pragnency test by kit but result is not pragnent and there after on that month ie 27 of jan i got my periods.but in my periods again we did sex by safety by getting condom ,and also i get i pill after 12hour of sex..after that i again do check twice time of pragnancy test by kit by the morning urine.but in the month of fevruary i did not get my periods and since today is 6 th of march i did not get periods..why doctor??is there any side affect of i pill which i took at the time of previous period??please give satisfied result.as i am not married girl .please give satisfied reply .also i can say that as pragnancy women feel vomiting,stress ,or any other like this .but i did not get like this..