Do you think I'm pregnant?!

I took this test yesterday morning and it's faint but it's there. Then I went to the doctor and they did two pee tests and they were both negative. So I came back to work and I did one more test and it was faint. So I called my sister since she works at the doctor and she said that first response was better then the ones they used so just keep my head up. She said to take one this morning and I did and it was still super faint. 
I'm just lost and I'm not sure what I should do!??? I would only be 4 weeks and 1 day!
What are your thoughts????