Should I Be Scared??

Me and my boyfriend had sex and when he finished he checked the condom and there was no tear so everything was cool. I haven't gotten my period but it was supposed to start on the 26th and it's the 29th but I'm starting to kind off freak out because it was my first time. Should I be scared? Or is this totally normal to be a little late? I'm still irregular since I barely got my period last year. Am I just over reacting?? Please help! I need advice