confused and need help

okay so i have the nexplanon implant and my boyfriend and i have been having lots of unprotected sex lately. he's also been cumming in me too. but i took a pregnancy test a few days ago and it came out negative. the confusing part is that my period is roughly 14 days late according to <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a>. my periods have always been irregular but i had a few days of spotting so idk if that was basically my period for the month or if i'm just not going to have one this month. 
someone please help explain this to me