hello, i was on antibiotics for 8 days, the chemist told me they reduce the effect of birth control whilst taking them and for 10 days after.( i have to wait more then 10 days as a started my sugar tablets the day i finished the antibiotics). i have only been on birth control for about 2 months. i took my first sugar tablet on friday, last time i got my period on the 3rd day of sugar tablets, it is now the 5th and i havent gotten it. I have only had sex twice after the antibiotics, once using the morning after pill and once using a condom. i have been sick with a throat infection and cold and flu and i have also been stressed from school for a few weeks. any suggestions on what i should do and why it hasnt come?