With a cycle that varies between 29 and 31 days, ovulation (the time when an egg is released) usually happens about 14 days before your next period, so in your case, it is likely around day 14 to 17 of the cycle (counting the first day of your period as day 1). The best chance of pregnancy is during the fertile window, which includes about 4-5 days before ovulation and the day of ovulation itself, so having intercourse every 1-2 days between around day 10 and day 17 can increase your chances. Sperm can live inside the body for a few days, so regular timing during this period is more important than focusing on a single exact day. Maintaining a healthy lifestyle, reducing stress, and avoiding smoking or alcohol can also support fertility. If you have been trying regularly for several months without success, it is advisable to consult a doctor for further guidance.