Cycle day 29. Implantation Bleeding? Is this possible?

My cycle is usually 26 days long. So technically my period is 3 days late. For the last 4 days I felt like my period was coming and on and off wearing tampons. For the last 12 hours I’ve noticed lite brown/pink staining on the tampon with a few scattered bright red spots, almost like pricks. No clots. No flow. Could this Be implantation bleeding?

I’m going crazy reading all the comments and articles because they all say something different like implantation bleeding doesn’t come this late or it should never be bright red. Then I read comments and people share their experiences that say the opposite.

So far all HPTs are negative. I never got my usual pms symptoms (sore boobs, etc.) And of course I’ve read that a positive test takes about 3-4 days to appear after implantation bleeding. Which if it happens would be my cycle day 33. A week after AF was due. Is this possible?