Implantation bleeding or start of period?

I had unprotected sex last Sunday (9%) and Monday (11%) during my fertile week (did 5 strokes in me on both days) but he didn’t bust in me (going on two weeks now since it happened) and of course pre cum was present. Two weeks since I’ve took a plan b (Tuesday after the quick sex) and I should be expecting my period in 6 days... I currently have had tender breast since the 18th (10 days before expected period) what do you guys think??