Hello Doctor! I Am A Mother Of 1-year-old Kid. I

Hello doctor! I am a mother of 1-year-old kid. I am breastfeeding her. My periods are regular and usually comes at 17th of every month. Her birthday falls on Feb 20. We have planned ayush homam. My in-laws are very orthodox. So i want to postpone my periods till Feb 21. Is there any safe medicine which will postpone my periods at the same time not harm my baby? Thanks in advance