I took plan b and its been 14 days after, but im on birth control should i b concerned ab pregnancy if i took a test last friday and it said negative?

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 by 3 weeks after sex (3 weeks after when conception might have happened). Emergency contraceptive pills can alter the menstrual cycle bleeding for the current cycle and sometimes the next cycle.