Bf pulled out. period 6 days late but could be late due to stress or diet change. took 2 at home tests, one am 2day, both neg. should i still worry?

Pregnancy unlikely: 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.