It's possible You might not be ovulating. Some women can go a few months without ovulating and you might not be having intecourse at the right time.
Best time to get pregnant is up 3 days after your period depending on your cycle. Spurn can live 1-3 days max 5 days in the best condition inside of the women.
Take the ovulation test sold over counters to best know when is the right time to become pregnant.
After you ovulate your egg Dies in 24 hours in which you will not get pregnant.