Here is a link to a great little article by memoir writing coach Marion Roach Smith. I love her concept of "taking a slice" out of a student's timeline and admonishing them to "just go from here to there."
There's nothing wrong with writing an autobiography if that's what you want to do. But it doesn't need to be comprehensive. Find a few of the most interesting "from here to there" bits to focus on the highlights of your life.