Practice your stories and answers out loud. When you practice out loud you become more engaged in your own story, more passionate and more confident. You have structured the content so you will remember it. There is no need to memorize. It is your own story after all. As you practice you will start to remember more details. As you start to take inventory of all your successful outcomes this will increase your confidence. At first it may seem awkward and you will be tempted to be overly critical of yourself. Keep going. Keep it positive!
Channel your energy and think of it as self-feedback and an opportunity to improve upon it. You will surprise yourself as later in the same day you will still be processing things that you could have said or want to fact-check. Quickly take the self feedback and write it down. Organize the new information back into your story. Simply go back to the preparation stage if you need to and each time you practice will get a little more confident. Practice your stories with friends. Welcome the feedback as valuable. Filter as you wish. You are in control. It is your story. Go for a mock interview with a professional for maximum impact. Write down the feedback and then practice out loud again.