Should I test again?

Sorry for the tmi but I need help, I was sopossed to get af on Tuesday but I had been feeling off and weird for a few days before so I decided to take a test Monday before my missed period them when it didn't come on Tuesday I took the second test (because the come in a pack of two) both tests were negitive so I thought nothing of it, I am never late so going three days and still no sign of af is starting to make me think something else is up. I have been feeling on and off again nauseous and I've been getting weird almost cramps but not like normal cramps... I don't know if I should wait a few more days and if nothing's changed test again or if I should test now. Is it possible to test negitive if you tested to early? Please help