Late period for 31 days. had intercourse and used protection. no pregnancy symptoms. this happened to me before. what is happening to me?

An irregular period: Irregular periods are one of the most common problems obgyns treat. If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. There are many options available to help regulate the menstrual cycle. If you think you might be pregnant check then check a home pregnancy test. They are cheap, reliable and available at any pharmacy.