Hello Doctor ...from Past 1 Year Am Using Regesstrone Tablet

Hello doctor ...from past 1 year am using regesstrone tablet for every 3 months as am not getting my periods regularly ...my doctor who did my delivery suggested me to take this tablet after checking that there is no thyroid or haemoglobin effect for me...she suggested to take this regesstrone tablet..wen ever I took this twice a day for 5 days I will get regular periods for 3 months after dat my problem coming again and am using regesstrone tablet again...right now am in US...is there any problem for my further pregnancy or suggest me anything to get regular periods

thank you