Hi Doctor. I Took 4pcs Of Nordette As An ECP

Hi doctor. I took 4pcs of nordette as an ECP last feb 3. And took another 4 pills after 12 hours. I got my withdrawal bleeding on Feb 20. The bleeding was heavy and lasted for 4-5 days. My boyfriend and I had an unprotected sex during my ovulation day (March 7). He didn't came inside me. And now, i'm 4 days delayed. I'm supposed to have my period this March 21. Also, i've taken a pregnancy test for 3 consecutive days, first test was the day i missed my period and took the 2nd and 3rd test for the next following days. The result was all NEGATIVE. Since the day of my missed period until now, i'm experiencing abdominal cramps but w/ no vaginal bleeding/spotting and breast tenderness. I also felt nauseous and have experienced headaches. Am i pregnant even the results are negative? Or is it the side effect of nordette pills? I'm worried. I need your advice. Please help me. Thank you.