Negative pregnancy test...

So I'm almost a week late when it comes to my period, which isn't normal. I'm sometimes a few days late, but not a week, by tomorrow. I wouldn't have a period all month. So I took a clearblue test two days ago, after my missed period, and it said "not pregnant". I still have started, and I'm having pregnancy symptoms, not period symptoms, I just wish I know what was going on in my body.. Am I pregnant or not??