Should I wait longer?

I'm going on day 4 of my period being late with no signs of it coming. I've had 2 negative tests though. Also, I know that your cervix isn't an accurate method of predicting anything, but my cervix is usually so low and easy to find before AF. However, the last two days it's been so high that I am having a hard time finding it. I used those Walmart 88 cent tests, should I try a different brand? Should I wait until next week to test again? I'm so confused because I've never had a cycle this long.