The best way to go about this is to get a basal thermometer and track your temperatures. When your temp spikes up pretty far then you are most likely ovulating or going to ovulate. Which is your only time during your cycle that you can get pregnant there is only a two days before and one after in which you ovulate that you can get pregnant and the egg is still alive so you must find out when this is. The easiest way is to have sex every other day from when you end your period until you get your next one.
Me too, but If I take birth control I am regular. I quit taking them and now I am back to three months.