Who has had implantation bleeding? I need help

Alexis • 17, mommy to baby boy
Started implantation bleeding on 7 dpo. First it was light brown on panty liner than light pink when wiping. Got heavier and lighter as the days go, being light and dark brown. (10 and 11 dpo) its a heavy dark red. Is that normal or should I see a doctor? The timing that the implantation bleeding was right on time. 
And I know it's not my period because I have EXTREMELY bad period cramps on day 1. (And the spotting made me know it's not. Because I never get it) 
And Also my period was supposed to start tomorrow. TTC for 8 months. Please and thank you