Implantation? 6-7dpo

So today I’m have very light brown spotting which is super unusual for me at only 6 or 7 dpo. I always spot the two days before my period arrives but never outside of that and my period isn’t due for another 7 or 8 days. My cycle is usually around 30-31 days. Glow said I ovulated on CD 17 but from my symptoms, chart, and opk I think I ovulated CD 18.

I guess my question is when do you think I ovulated from my chart and has anyone actually had implantation bleeding as early as 6 or 7 dpo?

Thanks!