5 days late and spotting

Okay so my AF was supposed to show up by now I'm 5 days late. I took a hpt about 3 days ago and it was a bfn. Now I'm having cramps but still no AF a little spotting but that's it? I was over checking my calendar and seen that implantation bleeding happens withing 24-72 hrs of intercourse. Could this be what's going on or am I holding on to the thought of getting my bop this month??