First Time TTC...HELP!!

My husband and I are on our 2nd month of ttc. AF started 1 day early and started with some light pink spotting then brownish then became heavier and red with some clotting. However, this only lasted a couple of hours and now I'm back to light pink spotting. Typically af only lasts about 2-3 days for me and is not very heavy. But this is very unusual. I took a hpts at 12 dpo and got a bfn. Could this be implantation bleeding? Afraid to take another test because of the bfn.