Questioning religion.

I'm 14 and I'm seriously doubting my beliefs in religon. I went to a catholic private school throughout my whole elementary school education and never remember enjoying or even being excited about going to church. I've realized that I don't believe much of what is said in church and am having serious doubts about the existence of God. I'm the type of person who is inclined to believe proven things, but that's not an excuse. I think I'm atheist. How do I tell my parents?