No Period Yet!!!!! Please Help

Samilya

I Last Got My Period On December 8 2017 . It Always Comes At The Same Time Every month . It is the 15th and I still have not had my period. I took a test on the 5th and it was negative. DID I TEST TOO EARLY? IM SCARED TO TAKE ANOTHER ONE ;I DONT WANT TO BE DISCOURAGED. PLEASE HELP