Hi, when you are on the pill, there is less than a 1.5% chance of ovulation or getting pregnant, but the chances increase if you miss more than 2 pills in a row.
when you are on the pill, it does many things to your body>
1- it prevents ovulation, so no egg is ever released
2- it creates an acidic environment to kill sperm
3- it dries up cervical mucus so there is very little chance sperm can enter the uterus
4- it creates a very very thin uterus lining, so thin that even when an egg is fertilized, it has almost no chance of implantation.
so if you missed ONE pill, i personally think there is very very very little chance you can get pregnant. but if you are concerned, test in 12 days.
the pill works in a very different way with different women. some women take half a year or long to conceive after the pill and some conceive rightaway. talk to your doctor about when to stop and when to start ttc. good luck!