Sex week before period. period was very light for 5 days. neg test 19 days after intercourse. accurate?

Yes, likely accurate: Women ovulate (release an egg) 14 days before their bleeding starts. Having sex a week before your period misses the fertile period by a few days. That being said, do not have unprotected sex if you do not wish to be pregnant! Conception has a way of happening.... If you develop sore breasts, are late for your next period or are increasingly tired, repeat he home pregnancy test.

Probably accurate: Can retest in 1 week if still worried. 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 or 1 week after having a "weird" period. If done sooner, a negative result may be due to testing too early such as less than 2 weeks after conception.