I had my last period on 3 Jan and the next one was due at 31st Jan. I have a cycle of 28 days average.. n I had sex a couple times in the month of January on 7th Jan I had it without pretection so I took an emergency pill instantly and the rests were with protection . Now it has been 5 days since the date of the period which has yet not come. I tested with home pregnancy test in the morning after 3 days if the expected day arrival of period and it came out negative. What could be the reason for this and what should i do now?