Missed period , 6 months pp

So I had my first pp period a month ago, i assumed I would probably still have the same cycle length as before I was pregnant, but it’s my third baby and every pp healing is different. So the day before my predicted af I had super light pink discharge, like so light is was hard to even tell it was pink. It lasted 2 days and since then I have had nothing else. I’m now 4 days past my predicted af and there’s no apparent signs of it being close. I took a pregnancy test the day of my missed period and it was negative. I know pp periods can be irregular, and I’m still nursing a little at night, but now I’m wondering “ could that super light pink cm be implantation??” My cm has increased since then. My husband and I are definitely not trying, so we have been carful. Anyone else experienced this? What was your outcome?

I think I might take another pregnancy test today just to rule it out