Implantation bleeding or period

I had unprotected sex the 21st of August. 3 days before ovulating. I have had many signs of pregnancy. I’m supposed to get my period the 12th but I started bleeding on the 7th. It was light pink and only when I actually went to the bathroom and wiped. I did put a tampon in and when I would take it out it was barely anything, light pink and kinda brown discharge. My period never comes early. The bleeding is gone today. I took two test the other day but both were negative. How do I know if it was implantation bleeding or period even thought that’s not my normal period? If I don’t get my period the 12th like I’m supposed to do I assume I’m pregnant and take another test?