I was 5’6 when I was 12 years old. By the time I’m 18 years old I want to be 5’8. I started my period when I was about 9 or 10. Do you think I would stop growing because I’m going to be 14 years old?
Age has very little to do with predicting how tall you will eventually be. We use ages only as general indications when certain events occur in the typical teenage girl. However, there is nothing in your body that keeps track of time and says, “Hold on, I’m fourteen today. Time to stop growing.”
A better predictor of whether you are going to continue to grow or not is to look at which stage of development you are in and which events have already occurred. See the “Tanner Stages” for more details. The period of rapid growth typically happens during stage three, though it can start in stage two. During stage four the typical girl puts on one to two more inches of height and then stops. Since menarche generally happens during stage four (though not always), this is what leads people to say that a girl usually only puts on one to two inches after her menarche. To estimate what stage of development you are in, see the Tanner Stage Calculator for Girls.
Jesus asked, “Which of you by worrying can add one cubit to his stature?” (Matthew 6:27). Height is one of those things which is basically out of our hands. You might want to be 5′ 8″ at age 18, but your desire won’t make it so. You will be the height you turn out to be. That height will be mostly governed by the genes you inherited from your parents with nutrition and health playing additional roles. Learn to be content and happy with who you are and not what you think you should be.