My period is late. I'm confused.

Tiffany • Christian. Mother of 3. 3 living and 1 angel. 10 years together married 7.
Hello.
My periods come about every 32-35 days. I was suppose to get it on the 12th. Never came. So now it's the 15th at 35 days and still no period. I took 2 digital test, one Thursday night and one this morning. Both said negative. So why no period? Thanks for all the help in advance!