8 days late! Going crazy! Light spotting? Advice please!

I'm now 8 days late! Still getting all negatives on HPTs. Yesterday I had some brown discharge, then later in the day when I wiped I got some bright red blood. I was devastated, thinking I got my period. I wore a tampon to bed because my period always gets a lot heavier from day 1 to 2. Took out the tampon this morning and it was practically clean other than a little brown and pink. And since then I've been completely clean. Is the chance for pregnancy still there?! I've heard of spotting and implantation bleeding, but could that happen this late? Any advice will help! I'm going crazy!

(For reference, ovulated first week of Dec, had sex Dec 1 & 2. Expected period was Dec 16-18. It is now the 26th!)