How do i know if tested too early ? i don't have periods because im coming of depo-provera got my last shot 3 months ago.

3 weeks after sex: A urine pregnancy test done correctly gives a reliable result 3 weeks after sex (after possible conception). If trying not to get pregnant, one should get on a reliable birth control method now (and always keep condoms around). If trying to get pregnant, one can continue to have sex and just check a urine pregnancy test if no period appears in a month. An ob-gyn doctor helps, if no periods at all.