So this is probably going to be a bit long

On July 24 husband and I had intercourse and im usually really good with timing and I told him it was safe to just "go ahead" at the end..
I got a heavy bleed on August 30 , so obviously July went by fast and I was way off on dates. I have an almost 10 month old baby, and I got my period back about 5 months PP.
JULY 1 it started as a moderated bleed then completely dissappeared come mid afternoon.

The next 3 days I had zero bleeding.
The. August 5 I got brownish/light pink tinge mixed with lots of mucus, but only when I wiped.,never came out in pee or anything
August 6 I had even lighter ringed of pink mixed with mucus when wiped..and later in the day one lil streak of red blood. But that was it
Today, August 7 I had absolutely nothing, just what looked like one tiny lil spot of light pink on the pad, barely noticeable.
I have abdominal cramping and headaches And nausea on and off. All home pregnancy tests I've taken have come back negative.

I currently have 6 kids and have never experienced this.

Could I be pregnant? Or what else could it be?