Your GPA is pretty good. Always try to achieve the best grades. Those advanced classes are also a plus. If you can, you should join a sport. The USAFA is a very physically oriented school and most of the students there have done at least some athletics in high school. You'll probably take your PSAT in your sophomore year and most students take the SAT in the junior year. Judging by your GPA, I think you'll do well. Just keep up the good grades. It is also good that you contacted your senator already. It is good to let them know that you are interested. Remeber that you can also get nominations from other people such as your congressmen. Also, you should do some community service. I have heard that they look for at least 100 hours or so. Also, look into other extracurricular activities. For example, you could join a club and try to earn a leadership position. Also, there is JROTC and the CAP.
Good luck.