6 days late! all my tests have been negative!!!!

Whaaatt is going on! I'm certain I'm pregnant. I have nausea and vomiting. My breasts are tingling and heavy, I have constant head aches, my vagina is constantly watery, all I want to do is sleep.. and every time I take a test it's negative.. idk what to do or think. I don't want to get my hopes up but what the heck!