I took a pregnancy test at 6 days late and it came back negative. could i be pregnant? if not why is my period so late?

Late period: There are several possibilities. The level of pregnancy hormone may not be high enough in the urine to turn the test positive. Could see a doctor to get a blood test to confirm even at 6 days late. Hormones could be out of balance. Certain medications can affect the cycles, even birth control pills. Stress and even excessive exercise can cause some women to miss periods. Check with your doctor.

Blood test for HCG: Get Blood test for HCG Menstrual irregularities are not uncommon and anovulatory cycle is a common cause. If you miss more than two periods it would be time to see your doctor. If you do not wish to be pregnant, use contraception all the time. You may consider implanted contraceptive or an IUD. Consult this site. http://www.nichd.nih.gov/health/topics/menstruation/conditioninfo/Pages/causes.aspx