13 days late

Okay so I’m 13 days late I tested at 6 days late and it was a bfn. A few days ago I thought af was coming because I had a little blood in my underwear it she never showed..since I have no idea when I ovulated could that be implantation bleeding? Af usually comes within a day or so of when she’s supposed to. I’m not stressed or anything either I’m not sure what’s going on..