Implantation bleeding? Chemical? Early AF?

Peeps, I'm losing the plot with all this.. I'm 9dpo and just starting bleeding...with my first pregnancy I had heavy implantation bleeding (as in I thought it was a normal period until I started feeling off about a week later and ended up being 4+ weeks pregnant). Last month I got a faint postive and then AF arrived, not sure if it was a faulty test or a chemical pregnancy. So now I'm not sure if I'm out this month! All test so far have been completely negative. Do I keep testing or accept that my period has arrived 5 days early? After knowing that implantation bleeding can be more than just 'light pink spotting' I feel like I dont trust my own body and its stressing me out!!!