implantation bleeding?

I had spotting lasting only 1 day 13 dpo. It was also the day my period was supposed to start but it only was light and lasted a day. I am wondering if it was maybe implantation bleeding. I have been having signs of dizziness and cramps. I tested the day after the light spotting and 3 days after but both came back negative. Am I testing too early or was that just my period being super light?