Irregular periods and hormonal imbalance

Hi!I'm new to this board and any input would be appreciated. I am concerned over the topic of having children,since I have a problem with my menstrual cycles due to a hormonal imbalance condition. I could go without periods for months. I have been put on different kinds of birth control pills to regulate my cycles but as soon as I stop taking them,my levels of progesterone,estrogene go back down again. I stopped taking bcp 3 weeks ago and still no sign of a coming period.Therefore,I don't know when I ovulate and if I ovulate at all.
Needless to say how I am concerned over the topic of becoming pregnant. I don't know what are my chances.
Any reply would be appreciated.Thank you.