Hi What is your age and BMI? If you are obese you must reduce weight. That is the common cause of hormonal imbalance resulting in irregular ovulation. Have you done any investigations before. Since you are not menstruating regularly it suggests that you are not ovulating regularly. As you conceived once in all probably your husbands semen analysis is normal. You and your husband should consult subfertiliy specialist . You need to do hormone test including thyroid function tests and Fallopian tube patency test. Your husband should do semen analysis. Based on the results of investigations treatment can be given. For irregular ovulation you need to take medications like clomiphene to induce ovulation. I hope I have answered to your satisfaction. Take one tablet of folic acid daily. To increases your chances of pregnancy, maintain normal BMI, quit smoking ( if you are a smoker) and have intercourse atleast three times in a week. if you have any further queries feel free to contact me through health care magic