Lets get your facts clear as you have put it - you had sex on the day your period was expected. One would not expect a pregnancy
on 1st day of period as this falls in the Safe Period. But your period didn't come as expected. If you had sex during the 20-25 days before the date of your expected period, or if you routinely have delayed egg release and delayed period, it may have resulted in a pregnancy especially since your period didn't finally come. The first diagnosis if there is a missed period is pregnancy. That should be ruled out by a Urine Pregnancy Test done on first morning urine.
You complicated the matters by taking emergency contraception
at the time of your expected period. That could further delay the period.
You didn't mention whether you often have delayed periods.
Yellowish discharge clearly indicates an infection. You will need to swallow some tablets for this as well as use a vaginal pessary. If possible, follow the standard protocol of tests for gonorrhoea
, chlamydia, hepatitis
. Please never, ever have sex without a condom, unless you are wanting pregnancy, to prevent sexually transmitted infections.
In view of your incomplete and unclear information regarding the dates of your periods etc, my first advice to you would be to rule out pregnancy by a simple urine test.