The best doctor to start with would be your OBGYN as they are the ones who deal mostly with reproductive Organs and issues… often if you are missing your menstrual cycle for a long. Of time it is a sign of hormone imbalance like with #PCOS or polycystic ovary syndrome in which long periods of time without menstruating are a common finding
If you are not having periods it means you are probably not ovulating. The cycle of hormones that makes you ovulate, also builds up the blood in the womb and releases as a period. So periods follow successful ovulations. Clomid can really help with inducing ovulation.