Thanks for the query.
If you had unprotected intercourse
around the time of ovulation, there is possibility of pregnancy
Sometimes urine pregnancy test kit may not detect early pregnancy.
So you wait for one more week, possibly by that time you will get periods.
If not consult gynecologist, get examined and go for ultrasound
This will find out the possibility of pregnancy, in case of absence of pregnancy, the cause for delay in periods can be made out.
And you can take tablets for withdrawal bleeding with your doctor's advice.