There is a line but if you're past your period it should really be darker. Are your cycles usually regular? Maybe you had a chemical pregnancy? It's unfortunate, but it happens where you pick up the pregnancy hormone and it shows on the tests, but it sadly tails off as the pregnancy ends, happened to me twice .
I've had faint tests like that and gone on to be pregnant, but that was when I was testing like 3 to 4 days before I was due on my period.