Thank you for your question. Your cycle length determines timing of ovulation which determines your chance of pregnancy.
You can determine the date of ovulation with ovulation monitoring kits from your pharmacy which come with detailed instructions for their use. Their advantage is that they take away the guessing game of whether or not you have ovulated in this cycle. As long as there are fresh sperm in your vagina 48 hours either side of ovulation you stand a good chance of getting pregnant. You need to be taking folic acid to help with baby's neural tract. Apart from that no medicines are required to get pregnant.