Implantion bleeding or period??

Maddy

So i’m currently 4 days late for my period. i’m always on time or early never late . off and on the past 3 days i’ve had this . with a bit of watery brown discharge as well. thick snot like discharge or sticky discharge everyday since ovulation as well. I’ve taken 2 test and both negative. what could be going on? i had implantation bleeding my last pregnancy and it looked like this .