In all honesty, the young woman I was when I was at the start of my high school years is different from the middle and the end. Truthfully you never stop growing, and if you are not being pushed to grow than stop and look around. You want to constantly grow as a lady, an employee, a student, mom, or whatever your duties may be. This allows you to grow in your wisdom, strengths and how resilient you are.
Looking back at when I was in high school, I felt that everything was so stressful and it was pointless for us to have to be under all that pressure. But it truly shapes and prepares you for the next chapter that you will face. This might seem scary for you at the time, but God truly knows your heart and future. And while he knows these things, he knows how you will need be to shaped and prepared for those times.
There are moments that constantly are occurring, positive and negative that if I did not go through all that I did back in my HS years, I would not be able to handle them so clearly and wisely. Of course, there are some that have to face things that truly don't seem realistic at that age, but it shapes them into who they need to be. So with this being said, instead of saying "Why God," turn that into "Thank you, God."
I praise you because I am fearfully and wonderfully made; your works are wonderful. I know that full well." — Psalm 139:14