Period or implantation bleeding?

I’m three months postpartum & exclusively breastfeeding. Yesterday, after about four or five hours of running around, I went to the bathroom & noticed I had bled nearly through my underwear, like a dark reddish brown.

I came home, got cleaned up (my stupid butt didn’t think to keep pads on me for when my first postpartum period decides to show ugh), and went to bed.

This morning i woke up & hardly bled at all last night (like two or three spots that you’d be lucky to even call a “drop” of blood), still dark reddish brown.

I’m only “bleeding” when I wipe.

Sorry for the tmi/pic but can anybody tell me if this is implantation bleeding or just my first postpartum period?

I’m a little panicked right now. We love our daughter more than anything and are not ready to make her share her mommy and daddy with a sibling yet!

Thanks in advance.