My period

Soo I got my period for 10 days and it was normal for me.3 days after that period I got another period but this one only lasted 3 days, and so I was suppose to get my period this week but it didn’t come. Should I count the 3 days as a new period or count the 10 days Because I haven’t gotten my period for a week now and I’m afraid of being pregnant. (Its complicated I don’t know if you all will understand)