Help....

Jordan
I'm quietly freaking out on my own and need help/advice. I've never had my period late in my life. I'm 18 years old and always start on time and my cycle lasts 7 days. I'm now 6 days late...I've taken 2 pregnancy test and both resulted in being negative. There's no signs of my period starting since I always have awful cramps. What other explanations are there?