What's up with my plumbing??

Sara
Ok so since the birth of my son(C-section) my cycle is crazy. My son is 9 months old now. The first couple months after I stopped the after birth bleeding, my cycle pretty much went back to normal. Around 28-29 days between periods. Normal, right? Then it started getting further apart...like 35 days...39 days...up to 41 days! What's up with that? Maybe it's normal? I am an exclusive pumper, so could that cause a disturbance in the cycle? It just bugs me because I like things to be on time and this is certainly not. Any ideas? Or just anybody who can relate?