My period is a couple days late , i had brown discharge a week before it was supposed to start i had a negative pregnancy test?

Tests are accurate: Today's home pregnancy tests are very accurate and not affected by foods, herbs, common illnesses, sexually transmitted diseases, or medications. A correctly done urine test will give a reliable result 3 weeks after sex (or when conception might have happened) or 1 week after missing a period. If tested sooner, a positive result is likely real, but a negative result may be due to testing too soon.