Spotting while Breastfeeding? Period or Pregnant?

Still breastfeeding my 18 month old. Haven’t had one cycle. Three days ago, I started very very light pink spotting with lots of CM. No spotting yesterday. Lots of cm today with light spotting again.

Does this usually point to first post partum period or possible pregnancy? Just had positive OPK three days ago too. Negative pregnancy test so far. CONFUSED!!!