What Causes Delayed And Prolonged Periods?

Hi, usually I have a cycle of 34 days. This time round I had a cycle of 40 days. It means that my period was delayed for a week. Suddendly, had my period and it is lasting for more than 9 days. This is my first time having a long period and mine is usually regular. I would like to know whether I'm enountering period now or early pregnancy bleeding.