Thanks for query,
First of all don't take pills to prolong your periods.
Just follow the instruction on pack as it should be started on 5th day of your cycle & continue to take it regularly for 21 days & then stop it so that you will get withdrawal bleed.it is good that you have taken missed pill on next day but don't use it to postpone your periods when you continue to use it as a contaceptive.
As you have unprotected sex while you have bleeding on there were no chances of pregnancy
Just stop the pill now gets withdrawal pill & then after 5 th day start it as mention on pack.