10 days missed period,little backpain,breat tenderness ,negative prgenancy test?

Tests are accurate: A pregnancy test gives a reliable result 3 weeks after sex (3 weeks after when conception might have occurred), 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, and thus lead to a repeat test. If still worried, can repeat a home urine test after another week.