It sounds like you have lots of pregnancy symptoms. Since you're getting negative test results and you're 6 weeks late I'd schedule an appointment with your doctor to check and make sure nothing else is wrong. Best of luck!
Make an appointment and go to your obgyn. And ask for a blood test and that's the most accurate test you can have , sometimes pee sticks don't work 4 everyone you can be part of that % , just go get confirmed and tell them your late, god bless you (: