13 dpo BFN

I'm 13 dpo, af due tomorrow. Took test this morning and BFN. I'm super depressed about it. I figured it would Def show positive. I've had all the symptoms and even think I had implantation bleeding, because I never have mid cycle spotting. Any hope for it to show up in a few weeks? Anyone else tested day before af and then got bfp a few days after af was supposed to arrive. My instinct tells me I'm pregnant, but I'm loosing hope. Is it likely I could still be pregnant and just not showing up on hpt?