I had sex unprotected & now i'm scared i wont start a period. i've had brown discharge & blood when i wipe, but had 2 negative pregnancy tests help?

Do test when late: You will want to repeat the pregnancy test if your period doesn't come at the expected time. The test works by measuring the amount of a hormone in your system called hcg. Most of the tests are set to go positive at the amount of hormone that'd be in your system when your next period would normally be due (about 20 mcg). If you test too early it may falsely say negative.