Is it overthinking ??

Me n my boyfriend had intercourse on16th july which was protected and i had plab b after too for extra precaution and i experienced spotting that month a but i got my 5 days period that month too after i got my blood work done on aug 8 that came out negative and I didn’t had any intercourse since then but i got my period only for 3 days in august Nd m always stressed about being pregnant i dun kno why this thing is not getting off my mind what should i do ??