July 15 is my first period.i had sex july 26..i take pregnancy test and its negative...but im waiting for my period since august 15 ..am i pregnat?

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