Can an I-Pill work effectively if taken within the stipulated time?

Hi doctor,

When I took it the first time, we did not have sex properly, but we got confused, so I took tablet Unwanted-72. That was four months back, and since then, my periods have been normal. Again we had unprotected sex three months before and took tablet Unwanted-72, and my periods were normal. Then we mostly had unprotected sex, but we discharged them outside. I am still having some doubts. I took a pill two months back and one more pill in the same month. I noticed in that month my periods started in the first week, but the bleeding stopped in two days, which otherwise comes for four to five days. Then again got my periods in the first week of last month, and the bleeding was on and off. Seven days of bleeding means a disturbing cycle, but I took a pregnancy test later that week, and it was negative. But my next period should have come by now, and I have still not got it. So I took a pregnancy test again, and it came as negative. So I am late by six days.

Please help me, doctor.

Thank you.