5 days early or no?

Kimberly

So I have been crampy and gassy for the last few hours. I have been so busy at work that when I finally was able to go to the bathroom, I just had a feeling that AF reared her ugly face. Sure enough light pink on the TP and still cramping. I am not due for AF til the 21st and I am 9DPO. I am going to assume that AF has arrived, but after reading some of these posts, could it possibly be implantation bleeding??