Skipped period ?

Hey Y’all ,

so I figured I’d come to this platform to get some opinions. I was really stressed the month of December with finals, interviews for job opportunities and working retail during the holidays. My last period was November 10th . I’ve taken pregnancy tests one yesterday and one a week ago and they both said not pregnant.(My boyfriend and I live together so we have been having sex often) . I’m a bit nervous and have been cramping every now and then for the past 3 weeks but no period . My friend said maybe it’s just my period resetting. It’s usually regular sometimes off by a few days but a whole month without one is making me nervous. Help a girl out ! Drop some knowledge in the comments below . Thank you in advance.