I realise that you got your period now, but women may not have periods with the POP.
This type of pill can work in two ways. For all women it causes changes in the cervical mucus that will stop the sperm getting to the egg. For some women, particularly if you are a bit older, it can also stop you releasing an egg
Because there is no pill free period you will only get a bleed if the pill has not stopped you ovulating. For those women who are stopped from ovulating, there is no period.
Scary as it can be to miss a period, for some women it atually means they are better protected from an unwanted pregnany