All women don't have normal and regular periods. If you have painful or very heavy periods, it does not necessarily mean that you will have problems in conceiving unless there is an underlying cause like fibroids, endometriosis or a pelvic infection. However, if your symptoms are severe, you may be better off consulting a doctor.
If your periods are infrequent and irregular, it may be difficult for you to plan out your most fertile time accurately and you may need medical advice on working it out.
You may find Ovulation Tests to be very useful.