Implantation bleeding or pregnancy?

Hey ladies, I'm due to start my period the 17th. I start bleeding today out of nowhere with some light cramping. the blood is like a super dark red/brown. every time I go to the bathroom there is less of it. Today is approximately 6-7 days after I ovulated and my hubby and I are actively trying to get pregnant so we had sex everyday for two weeks after my LMP. Can it be implantation if it's not light colored blood? or am I just having an off month and started my period 8-9 days early?