Question for Mommy's.

Since I've had my son a year ago my period has been landing on different days each month(couple day difference). Last month I had my period the 8th and the month before was the 5th. Now it's the 10th and I'm having no signs of period. I'm starting to wonder if I'm pregnant but I don't wanna assume it. Has anyone had these problems with periods landing on different days every month? If so is it normal?