?Light blue line??????

Here's the deal, today I took a test from dollar tree, it showed a faint positive IN THE first 4 min, box said no longer than 10.... But after 20, it faded away. So I bought 2 cvs brands. Took one, it showed a very faint blue line, a friend took it n said she wanted to be sure so she took it apart, n it showed two blue lines, but to me I couldn't tell if the one for positive was grey or light blue.... She said regardless its positive but I just don't know... I'm due to start here in about 4 days now.... So it's still kinda early to test... Could it have really been a positive? I plan I testing again Tom am with 1st pee, then again if I miss my period.... Just curious...