You are in my prayers. I was called into missions when I was three years old- don't think that your age can keep you from it being a true call. I would suggest praying about this a lot, and also talking to your parents, youth pastor, and/or other mentor. Find out as much as you can about missions, both within the United States, and in foreign countries. There is so much that missionaries do, and knowing as much as you can about it will help you recognize if it's something you want to do, or most importantly, something God wants you to do. You could also contact missionaries and ask them about their experience. Tell them you want to know more about the mission field.
May God Guide You,
missionarypoet