How long has it been since your last period. When I first started testing you had to squint to see the line. It's best to test with your first pee in the morning because the most hormones will be stored up. If you are taking tests within minutes or an hour of each other you won't have enough hormones in your urin to show a positive result especially if you haven't missed a period yet.

Try using a first response pink dye test. Sometimes the blue dye tests are tricky. Good luck!

I still haven't got a positive test yet and I'm almost 7 weeks...

Is this your first test? If so, take one in two days and if it doesn't get darker it means your HCG levels aren't doubling and could be what they call a "chemical pregnancy." Good luck!