double mensies? HELP.

my son (3rd and final kid) was born on August 12th. he won't latch so i pump and supplement with formula. i got my first postpartum period 2 weeks ago. it lasted 5 days, medium flow. ive been on the mini pill since my 6 week check up. i just got my period again. no, its not just a little spotting. my panties are in the trash and my leggings are soaking in oxyclean.... wtf? anyone else get this? i don't remember rhis happening with my last 2 kids.