Late Period

I lost my virginity a little over a month ago, and as a general side note I haven't had sex since. I'm on cycle day 45 and tomorrow my period will be 2 weeks late. I took two pregnancy tests at 1 1/2 weeks late and they were both negative. He wore a condom but did still cum inside me. My period has always been regular... and I know I'm not stressed, I actually just got back from a months long vacation. Any ideas why my period might be so late other than pregnancy? I was thinking hormonal imbalance since it was my first time? Or the possibility I synced period cycles with a friend? Has anyone shared the same experience?