There's always reason for doubt. I do not blame you for considering the "well why would it work for me" or "what if it doesn't"
It is however, a proven and reliable method. There's been several threads that have been documented of users trying said method with the worst of their last messages being "I'm tired" or "I'm dizzy" etc
It seems like a solid plan for those willing to follow the steps provided, I can't say anything anyone else has said to take away your doubts, but from what has been shown on this site (from reliable sources and not random people ringing the bullshit alarm) it's a solid way to go peacefully.
At the end of the day you will always be worried about failure, or of making the act. It won't be easy, at least without a lot of practice, self-confidence, and commitment. I'm no pro-lifer, but personally I believe people should try everything else first before CTB, but if that's what you want, that's what you want. I wish all the best of luck and peacefullness in their passing.