Two month old BFing and already having a period?

Jill
What is the likelihood that my bleeding for three days was an actual period?  My baby is 8 weeks old, and with my older babes, I didn't have periods until MUCH later. I think I was 9 months PP with my first when I finally had a period. 
I'm getting an IUD put in at the end of next week, but I'm worried that I've become uber fertile and will be one of those .01 %ers who gets pregnant on the IUD.   Well, not really, but I'm totally not ready to deal with more
Bleeding already.