Hello there , I just read about your concern. First of all, for your information, cigarette smoking or other drugs affect sexual function. Smoking does affect sperm count and motility adversely. Having said this, not conceiving following sex or having normal menstrual cycles does not necessarily warrant safety from or surety of sterility. If u guys indulge in unprotected sex for over a year and fail to concieve then we definitely need to think in this direction. I hope this helps you. Feel to consult regarding any further queries.