The things that you think and worry about now … friends, money, purpose… you will wrestle with throughout your life. Not all of the time but it will come and go. We adults often wrestle with such things in more sophisticated ways but we still get concerned about such things.
Develop your faith in God… it will help you and be a source of strength and hope throughout the years.
Be grateful for your school mates now and don't be surprised that when you hit 50 you will have wonderful discussions with them now that you were too afraid to have with them at 16.
And relax and enjoy life… study abroad before adulthood fully takes charge…take a class for fun when you can. Keep reading and learning.