Sorry to hear that sadie, you must be feeling very frustrated. Most women tend to ovulate around 2 weeks after their last period. So try to aim for that time of the month when trying to concieve. You mentioned you are not regular, so that is probably not helping in your quest to start a family. Have you ever tried an ovulation kit ? You can purchase them from a drug store or supermarket, and they can detect when you are ovulating. Also talking with your doctor or family planning clinic will provide you with some important information. Also try your local hospital, sometimes they have a family planning expert who is happy to talk to you about fertility and ovulation.

Good luck.