post C, is it AF?

I THINK I just got AF darn it! even though I'm fully breastfeeding every 4 hours. :doh:
I had a C and post bleeding went for 3 days then started a gain 2 weeks later (very light though) and went for 2 weeks, now at the 6 week mark AF arrives?? it feels like af and it's pretty heavy like af with some cramping but how do I know if it's AF or post bleeding starting up again? with my first DS I got af at 6 weeks but that's when I stopped breastfeeding, and I can't remember what happend with DD.

I also have my 6 week check on thursday :doh: he wont want to do an internal will he??? arg I was hoping for a bit of break now I have to look into birth control again..