Yeah, it's cool. It all depends on several factors like genetics, your body and how it works, and your height and weight. I knew this one girl who didn't start hers until she was 16 and it was because she weighed so little. If you don't weigh much, then that could probably be it.
Menarche occurs currently in America at about 12.5 - 13 years of age - but can be delayed due to poor nutrition or even excessive exercise. Worldwide Menarche occurs at about 14 years old. This is the biological transition of females from children to young women capable of bearing children. The pituitary gland in the brain acts like a timer and signals all of the other relative endocrine glands to begin the process - estrogen is used to build the first functional lining of the uterus (the endometrium) where fertilized human egg cells will implant in a healthy female. If you haven't "had it" by 14, and you're eating well, and not under prolonged heavy stress, you should see a gynecologist to get assessed - and tested so a treatment can be prescribed.