finally got my positive 9 days after AF due but....

Gemma
So i calculated how many weeks I would be from my last period and I would be 6 weeks if I go by that...but will I actually be that far along? I got negative tests up until 9 days late and the lines still faint to what it was when I was pregnant with my first..
Sorry for the long paragraph but what I'm trying to ask is is it possible to be less than 6 weeks as I have fainter positives?! 
Phew lol