I stopped birth control for 3 months now, first 2 months after stopping i still have period but this month it has been 1 week late. i didn't had sex?

Some thoughts...: In a woman with regular periods, some causes of a late period include: excessive weight loss or weight gain, increased exercising, emotional stress, having an illness, traveling, certain medications, hormonal imbalances, etc… Seeing a doctor is a good idea if symptoms are persistent, recurring, or worrisome. (Pregnancy is the common cause of a missed period, if sexually active.)