Implantation Bleeding

Well let me start this off by saying I don't think I'm pregnant at all. I've been under a lot of stress and I don't feel any different than before. But today I am 12 or 13 DPO and I have some really light brownish colored spotting...well with some EWCM....its so faint...so is it implantation bleeding or just my period starting really slow. Normally AF is heavy and I'm cramping from the get go...no warning just all out BOOM and it hits and I feel like junk. I have no cramps I've been feeling great other than a little tired from working a whole bunch...and then this super light spotting. Its strange. Not sure what the deal is but I'm sure you'll find out soon. AF is due on Friday. I have a feeling she'll show... Stay tuned.