I would just re-test in 1-2 days with first morning urine, don't get to discouraged just yet your HCG might not be strong enough to pick up just yet with the tests. I tested at 11dpo (days past ovulation) and got the faintest line ever, I then waited 2 days and re-tested with a First Response Digital Gold (I hate tests with lines because they play tricks on you) and sure enough within 1-2min I got a PREGNANT on the screen =0) I am now 25 weeks and 6 days pregnant with a healthy baby boy. Also if you go to www.peeonastick.com they will give you a list of all pregnancy tests and their sensitivity, hope this helps and good luck!
Even though they say you can test sooner, they still have a lower accuracy than if you actually wait until your period is due or if it's missed. Wait to see if it comes, and if it doesn't, retest with first morning urine. If that still comes out negative you can wait a few days and retest again with FMU, or you can make an appointment and request blood work be done.