plan b?

Tiasha

so i had sex with my boyfriend a week ago and my period was suppose to start like 5 days later and we didn’t use condoms... i took a plan b the day after, waited the day after my period cause i didn’t get it took a pregnancy test and it said i’m not pregnant, then i took it the day after that because i still didn’t get my period and wanted to double check and said i’m not pregnant... is it just because the plan b that i’m not getting my period?