My last intercourse was on february 26 and i had my period on march 17 but i didn't get my period on april. i am now about 2 weeks late. i already took 3 pregnancy test but they came out negative. is it possible that i'm pregnant or is it the stress?

Tests are accurate: Home pregnancy tests are very accurate and not affected by foods, herbs, common illnesses, sexually transmitted diseases, vaginal spotting, or medications. A 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 negative result may be due to testing too early such as less than 2 weeks after conception.