Pregnancy Scare

I’m having really bad anxiety over these past few days. I had sex on December 11 and it was with condoms. But I’m too scared because maybe it still leaked or slipped but he told me didn’t ejaculate inside. I got my period after 1 day of being late, it was last night. January 14. It was heavy last night and had clots. But then my period suddenly gotten lighter and I’m worried that it might be implantation. I don’t really want to get pregnant.