What Causes Delayed Periods Even After Having Duphaston?

My 14 year old was put on Duphaston from day 12 to 25 to help regulate the period. Ahead been bleeding for 22 days at a time with a 3 day break. They were extremely heavy and painful. After 6 months of Duphaston it as decided to take her off to see what her body would do. She has ne period back I June 1st. How long should I leave. It before taking her acknowledgment to the dr