Missing period

So I'm a week late.

I haven't had sex since the 16th of last month, I had a light period last month, but when several days went by this month with no period I took a test. It was negative, but still have not had my period. I didn't take the test first thing in the morning though. Is there a chance I could be pregnant anyways? I'm not sure what to think. I'm never late, I haven't lost any weight, and I've actually been fairly stress free, as much as one can be.