I was having perfect periods. But this time I missed my period.. I am afraid.. my date was 11th and today is 12.. it has never happened before.. pl. help

It can vary several days easily for a number of reasons... such as stress (physical or emotional) or illness. And at this point you are a day late..

How old are you and is there a reason to be concerned about a pregnancy... and has there been any unusual stresses this past month.