Confused 1 positive test and clue blue says not preg?

Wendy
Morning all!  
Wonder if anyone can help - or share experiences etc?
My periods are late by 6ish days - had sore boobs and feeing generally sick and emotion I just thought it's because my periods are coming etc.
Well done a test this morning and came up with a faint blue like see photo
In the first picture within a minute below its faint however with 3 minutes it was stronger see above.
Came home and I have done a clear blue test and it has came back saying not pregnant? I'm not still unsure if I am or not?  Was sure I was with the first test now really not sure.