Idkk if I'm pregnant or not

So after I had unprotected sex twice last week and this week I got plan b as soon as it happened (when he came in me) I took a test yesterday and today both came out negative. But I'm bleeding a little bit but it dosnt look like normal blood. I'm scared it might be implantation bc I read that if your going through implantation a pregnancy test will come out negative bc it won't be able to detect it. I'm worried bc also my period is supposed to start in 7 days.. Is it implantation? Or do you think I'm fine