I posted material at http://lukecall.net (under "why I believe"), but the most direct answer to your questions might be at http://lukecall.net/e-9223372036854605861.html and pages to which it links. Honest questions & feedback are always welcome.
(The web site is generated from my note-taking program. It is intended to be very skimmable, where one can click on links if they are interesting, otherwise one doesn't see the details. There can always be more editing, but hopefully it is useful. Maybe in the future some levels should have a summary document of the contents, so you don't have to click around as much to read it in big chunks. Only part of the code to do that is written--to generate single-document outlines from my note-taking program, but not yet to include them in the web site.)
Your conviction comes from the fact that you've read, almost daily, and contemplated over the Bible and the Book of Mormons, as well as read a good number of comments for and arguments against your position.
You also derive it from your life experiences, particularly those where you have either done or not done what you thought you were supposed to/felt good about doing.
Am I getting this right?
Were there any particular experiences or turning points when you may thought "Hm. Is that what my life is about?" or "Ah-ha! That is what I'm supposed to do!"?