Baby #2?

Okay so my husband and I currently have a healthy 4 month old baby boy my pregnancy with him was very pleasant free of major complications and I've been very blessed not have any miscarriages. Because he was breech I had to have a C-section. We wanted to immediately start planning our second child with the C-section our doctor encourages us to wait about a year. I am currently not on birth control (I've actually never been on birth control in my life) and we are not using any types of contraceptives. I have heard that after you have a baby your most fertile but we have not conceived. In the past few months my menstrual cycle has been really off. In the past my menstrual cycles were very regular. So basically my question is is it too soon to conceive? Is my body ready? Or why hasn't it happened?