Suggest Remedy For Irregularity In Periods

my wife who is 26 has been having periods that last one to two weeks at a time. But she just had a period that lasted 21 days she was off four days and is now back on again. She is not now nor ever has been on any type of birth control. She may have had a miscarriage last month we do not really know. The month before last her period lasted 21 days with 4 days off. She is taking a Woman's one a day prenatal and extra DHA pills and triple strength fish oil pills. We are trying to have a baby and the ovulation tests never show that she is ovulating after 60 days of use. Please help in any way you can thank you!