To confirm on what could be the reason in ur case u need to get an ultrasound done to rule out for any PCOs or any other pathology,also get ur
thyroid and
prolactin levels checked.
You would need a treatment for six months in order to help you get regular periods if any of the above conditions is confirmed.
Next Steps
tests required to avoid future complications as advised above
Health Tips
weight gain should be reduced if any by taking regular balanced diet and doing good physical activity.