sounds closer to my experience, even if there is potentially some regional difference as I am not from the states. I think I was barely high school when I realized I wasn't christian or even religious, something like 8 years ago. I have to go every Sunday when my mom stopped being inactive in the church. The thing that convinced me was ironically something that was told inside the church. Don't be a Mormon because your parents are and so you have to, but because you believe and I simply didn't. The more empirical inclination I had in how the world works simply contradicted all their teachings and realized I was agnostic once I got explanation of what that was.
Over the years my agnostic belief just got reinforced. Some people need a religion to have hope, to find what is right and wrong or a sense of belonging and just over the years developed those outside of them. Eventually I realized that if I found God is real, it would change nothing for me and if good people shouldn't get heaven just because they don't believe in God, is not a worth believing for. So if there is some god real over there and is actually kind, they won't mind what I believe, only my actions.