I have been regular all my life and now im 8 days late but got 2 negative results 2 days ago. i havent gone through weight changes, stress, no health problems at all, dont take any medication. what might be wrong?

Need more info: If you are a person whose menstrual cycle is very regular and suddenly it has stopped, we need to think about causes. Oral/IM contraceptives, pregnancy, stress, nutritional deficiencies, weight loss, excessive exercise, eating disorders, excessive weight gain, uterine polyps, ovarian cysts and mental health medications can all cause irregular periods. If you are concerned, see a DR. for evaluation