I'm 4.5 mo post and I still have enough discharge that I wear panty liners, changing them 2-3 times a day depending on activity. I wouldn't put the color as grey at all, but slightly green tint for sure.
It's principally coming from the granulation tissue which is now down to just one area, the other granulation was in a place that it was worn away in one long bicycle ride and no discharge there since.
The volume of discharge has reduced steadily but up to week 7 there was like 10x more, so that I was changing maxipads 4-5 times a day and only wearing hospital mesh underwear because it would still overflow. That stopped when I she'd the old epidermis, also my scent became nice after that.
If your scent is OK then I think it's just the healing process. I also introduced lactobacillus in the form of probiotics early on in the healing process, adding it to the occasional 10% vinagre douche.