Welcome to HCM.
Four to five days delay in the period is fine. I advice you to wait for watch for another 2 days.
If you had unprotected intercourse
there is always a chance of pregnancy
. If you have any doubt that you are pregnant you can confirm it by doing a urine pregnancy test.
I advice you to do test at least week from the date of missed period. It is better to use early morning sample of urine to perform the test.
I advice you to take the pill as prescribed by the doctor.
Hope I have provided the information you needed.
Wish you good health.