12dpo and 14dpo

I feel like my 12 and 14 dpo lines are the same. My period is due today but lines have been getting darker since 9dpo. I also track my heart rate with my fit bit and this morning it had gone down 2bpm. I know it’s not that much. But that’s what normally happens when I get my periods, and when I had my chemical pregnancy. So just internally freaking out a little.