Am I preg? Or is it early AF?

So AF is due today but I wiped earlier and I have brown cm it happened just once and it wasnt alot? And slight cramping on and off for the past couple days. I'm 14dpo according to glow. Took a test the other day at 12dpo and it was bfn. And my left nipple has itched all day today. What is wrong with me?