Possible implantation bleeding?

Kat

What does implantation bleeding look like? I was due on yesterday. today I had some light pink discharge and thought I was coming on but it stopped. The this <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> I thought I was coming on my period again so popped a pad on and had some light brown bleed but only a small amount and it's stopped again. I'm confused as my periods are really regular but a test had said negative this morning.

See photo in comments (sorry a bit gross)