Implantation bleed or Af?

I posted this photo yesterday, and got feedback about my vfls. Last night my husband and I had sex, and this morning I woke up with some cramping. I went to the bathroom, saw watery pink/bright blood. I laid down for a few min and when I went back, it was mostly brown with a tiny bit more red. The cramping seems to be more localized (when I get AF it just feels like my entire lower abdomen) and is inconsistent - ive just had it for about 20 min and it stopped out of nowhere. Today I am 4 days late (unless obviously, AF has arrived).

Any thoughts? It doesn’t feel like period cramps or other symptoms, but idk if I’m wishing myself to believe that. I’m keeping an eye on the blood, esp since my periods tend to be heavy initially.

Thanks!