Hyperthyroidism

Hey ladies. I am experiencing hyperthyroidism due to having rheumatoid arthritis and a miscarriage in January. While I'm thankful that it's not life threatening it has done a number on my body. My period is usually on time every month and now it's off by about a week. Some months it's early some months it late (leaving me to freak out and worry about being pregnant). I can't figure out how to fix my period on this app. It says I should have started yesterday but I'm not due until next Tuesday by my calculations. Is there a way to change it bc otherwise this app is useless.