I think I've become agnostic?

I've gone to a Lutheran church about every sunday for the past 5 years, but i haven't gone at all in the past 2-3 months. I've been confirmed and all now that I'm 15. Anyway, as much as i hate to say it, i do not believe there is any evidence there is a God, Heaven, or Hell. Same goes with following the words of the Bible and everything else. I just don't understand how we can prove it all exists. I haven't told anyone what I think yet, it's not the kind of subject you just bring up out of nowhere, ya know? So what I'm asking here is, does anyone else feel this way, like was once a Christian and suddenly threw your holy being away?