Questions on tests I've taken

When I posted my test of blue dye, it was faint positive. Some ladies on here were saying that it was a definite positive and some were saying it looks like an evap or indent and to take a pink dye test. I took 2 pink dye tests and some ladies said they saw a very faint line on them and some said negative and to try a different brand because these tests aren't good. Are the only "true" tests the digital? I know digital have to detect higher amounts of HCG so if I'm 6 days late and 15 dpo, how long should I wait?