I am 21 years old. My last periods ended on 18th may. I did not have an intercourse but just doubt that the sperm might have entered. I took I pill on 20th may within 24 hours. I got bleeding after 6 days. My period was dated 14 june but it has not yet come. I visited a doctor and had pregnancy test which came negative. This test was taken 7 days after missed period. He recommended a medicine to start withdrawal bleeding. Should I wait more or start medicine? Is there still any chance of pregnancy?