My doctor said I had my period at my pp appt and told me to start my birth control today

I had my appt on Thursday and it was light blood she told me that I looked healed so it was period blood. Flash forward 4 days later I had cramping but very mild, my blood is now dark brown and barely there and red blood only lasted a day. I always had a heavier cycle before I got pregnant . I’m almost 5 weeks pp, could this just be left over after birth bleeding? I’m unsure if I should start the pack since it doesn’t seem like a real period. What was your first pp bleeding like?