Late periods

Hey so I'm new to this and I just had a few questions, my friend doesn't get her period ever mostly because she's unhealthy and stuff but I've been hanging around her a lot and I've realized now my period is 3 weeks late! There is no possible way that I'm pregnant because I have never had sex but, I was thinking that my cycle synced with hers. Is that possible or am I just crazy? Would really love some feed back! Thanks