Period is 31 days late, negative hpts. what could be wrong? i have a history of one functional ovarian cyst

Likely hormonal : Your period is 31 days late, meaning your last menstrual period was about 2 months ago. I see you have done a home pregnancy test which was negative. If you are not pregnant, the cause may be hormonal. Irregular periods are a very common problem and can be treated. I recommend seeing an ob/gyn doctor for evaluation, especially if you don't have a period in the next two months.