Late period?! Or missed period? 🤨

Is there anything I can do to start my period? I’ve been with my boyfriend for a while now. He never came in me but my period been getting later and later. I used to get it around the 15th and last time it started on the 29th. We do the deed without protection. I also did a pregnancy test on the stick but it all shows negative. I haven’t got my period this month yet. Is this normal when you’re with a guy? My last period ended on December 4th. I’m new to this so I’m quite concerned.