Late and negative....

So I'm kind of excited but trying not to get to hopeful. I have been ttc for a few months now. I should have started my period last week but it never showed (I'm never late, my body likes to stay on time). I took a test last night and it said negative. Of course its frustrating. I'm unsure of what's going on with my body and I'm not able to go to the doctors until next week. Has anyone ever been pregnant with false negatives?