Hi,
Welcome to ehealthforum,
Prolonged drug use can affect egg and sperm production and maturation affecting fertility levels. The chances of successful pregnancy depend on many factors (ovarian, uterine, hormonal, stress etc). You should consider getting a complete infertility work-up done for you and your partner to see if there are any underlying causes for the infertility/inability to conceive. Timing of intercourse during your fertile days is also important for success. Hormonal issues, problems involving ovaries and ovulation, uterine problems, cervical or vaginal infections should be ruled out for you. For your partner, semen analysis should be done to rule out infections and to confirm the quality and quantity of sperms produced. Treatment as needed (based on examination and investigations results) would be started to help you get pregnant. Consider visiting your gynecologist/obstetrician for further evaluation and assistance. All the best.
Take care.