Implantation bleeding or period?

Has anyone had implantation bleeding and if so what was it like compared to your period? I thought I was supposed to get my period on June 12-13 and had no cramping or spotting at all until today. I only bled for a few hours at the most and not enough to even use half of a small tampon. And I went to the bathroom and there was no blood at all. Not even when I wiped. Any ideas on if this could be implantation bleeding? I took two pregnancy tests before I had the spotting and both were negative.