A question about the home pregnancy tests?

Im now 8dp embryo transfer I did a hpt on day 6 and it gave me a very faint + like barely seen. On day 7.5 I did another test with another brand and it was a faint but darker + on day 8 I did two tests same brand of day 7.5 and it was also a faint positive not darker than day 7.5. the question here is, is it a real positive or could the test be giving this faint line as a default. Or is it an evaporation line. I get all the results within 2-3 min after I test so its within the specified period.