Stressing

My period is 18 days late. I haven’t had sex ever. I had dental work last month. The week before my fertile week I was really sick and then during my “fertile week” my bf and I did oral but he said nothing was on fingers. I took a test when I was 3 or 4 days late it was negative. My periods can be irregular (one time it was 20 days late and then another time it was 35 days late). I don’t know if the dental work would cause my period to be this late? I know I’m stressing myself out because I keep thinking that I got pregnant somehow, am I just overreacting and overthinking everything?