Hi. So my period is 3 days late now. And i'm worried, I had sex last April 12 and

26. It's not my ovulation day and it's not in the ovulation window. So we had sex, we used CONDOM and also WITHDRAWAL. My boyfriend pull it out when he's about to ejaculate even if he wear condom. I'm worried because I might get pregnant. But before we had sex, I'm experiencing headaches. Sore nipples. Then recently, I'm having toothache and took some antibiotics for few days. It's amoxicillin. How come my period is late? It's been 3 days since i'm late. I got home pregnancy test and it was NEGATIVE. Do antibiotic really affect my period? Or it was i'm so stressed because I always think about this?

See pics below