Didn't start yet!!

I didn't start yet and I never had sex so I know I'm not pregnant but I'm 2 day late and I need to start by Monday or I can't go on vacation with my boyfriend family and my period is always weird and I'm going to get it checked this summer but I'm so stressed bcuz it's upsetting him bcuz I don't know what to do? Should I not go or go?? HELP PLEASE!!!