Did not have sexual intercourse. i got my period symptoms and quite a bit of brown discharge but my period is 11 days late. why won't my period come?

Late cycle: Irregular bleeding like this could happen if you didn't ovulate. At 18, this could be normal. However, If this continues, this type of bleeding can be associated with a hormonal condition called PCOS or polycystic ovarian syndrome. It can cause irregular bleeding, weight gain, acne, abnormal hair growth. See a Dr if your cycle continues to be abnormal for evaluation.