Hallow Dear, If your menses are so irregular, the chances of your ovulation are quite poor. However, you may monitor your ovulation by one of the following methods: 1. Ovulation monitoring kits can be used at home which will inform you if and when you ovulate. 2. Ultrasonography ovulation monitoring is the best way to monitor ovulation. It gives direct visual evidence of ovulation. Moreover it informs us about the number of eggs released, the size of the follicle ovulated and the thickness of endometrium at the time of ovulation. Follicle between 18mm - 21mm size releases healthy ovum with maximum possibility of successful pregnancy. So also endometrial thickness between 9 mm to 14 mm is highly conducive for implantation of fertilized ovum (blastocyst). By this information, you can plan your intercourse every alternate day when the follicle becomes 17+ mm size. For regular menstrual cycles, clinical way of locating ovulation to plan the intercourse is by calculation of the days. Ovulation happens 14 days prior to the next expected menses. Egg has life of 24 hours while sperms are active for 72 hours. Hence a period of about week to 10 days is fertile period. I hope this helps you. Dr. Nishikant Shrotri