What does implantation bleeding look like?

Hey everyone! I have been having some light spotting that is dark brown in color that started the day before yesterday. It's mostly only when I wipe and some very small spots on a panty liner. I've never experienced this light of spotting before af, so I'm wondering if it could be implantation? To be honest I have no idea when I ovulated. I thought it was the beginning of the month because I had ewcm, but now I'm not sure. Hubby and I did it the 5th, 8th, and 12th so if I ovulated later in the month it could be possible. I took a hpt this morning, but it was negative.