Post-partum bleeding or period?? Confused

How do I tell if i got my period or if its post-partum bleeding? Im about 8 weeks post-partum with a c-section and I stopped heavily bleeding around 4 weeks. The bleeding got very light after that and was only spotting some days. I thought I was in the clear at 6 and a half weeks because there was barely anything, but then bled heavily for 4 days. I thought it was my period at first, but the cramping was so mild compared to the unbearable cramps I use to get pre-pregnancy and it usually lasts for 6-7 days. I have a OB appointment set for next tuesday, but its impossible to get a hold of someone at the office these days. Is it normal to get your period so soon after birth? I dont breastfeed because I couldn't produce enough for my twins, does that have anything to do with it?