dear user, welcome to healthcare magic.
The pills you took have a very good effect if taken within the first 24 hours after having unprotected sex. they are less effective if taken after that.
Anyway, they are never 100% effective. and you say you have a missed period and that you never had irregular cycles. So, there is a chance that you are pregnant.
My advice is that you should have a blood test
and if the test s positive, you should visit your doctor to confirm presence of a healthy intrauterine pregnancy
and to exclude ectopic pregnancy.
if the test is negative you may either wait for spontaneous menstruation
or visit your doctor to prescribe you progesteron to induce menstruation.
Dr. Ahmed Bahaa.