First of all, you did unprotected sex on safe period if your previous cycle was regular. An other thing, you took unwanted 72 pill additionally for extra protection. It is effective more than 85% if it is taken in 24-48 hrs.
Period is delayed due to effect of 2nd time intake of the pill. You will get a withdrawal bleeding within 7-10 days. If you do not get it, you should undergo one home pregnancy
test or blood test
to exclude pregnancy.
Use combined OCP
as regular contraception
instead of emergency pill for highest efficacy. Consult with your gynecologist following test report.