Delayed periods. Of pregnancy now.

I had unprotected sex on 10 of june.. n that was 5th day of my periods... N within 3-4 hours i took unwanted 72...  after 7-8 days i noticed few drops of blood... But that was only while urinating... But after that my periods got delayed... My next date was 4, th of july.. as i have 28 days cycle... But my periods never came... My several HOME urine pregnancy test were also negative... after 24 days of period delay... My doctor prescribed me primoult-n , two times daily for 5 days... After stopping of medicine i got my periods    on 4 th day(after i stopped my medicine ie. Primoult-n)... Now i wanted to ask that is there still any chances of PREGNANCY.. n i bleeded normaly for first two days as a use to bleed... But now from the 3rd day bleeding is really less...but its still there.. normaly my periods last 6-7 days... So is there any point to worry... N is there any chance of pregnancy now...