Most people remain the same because they train and play in their comfort zone. You are not most people. You keep evolving because you are willing to do what's hard and uncomfortable. Remember if it doesn't challenge you... It won't change you.
Until you realize YOU are responsible for all of the thoughts in your head (positive and negative) you will always have issues with confidence and nerves. You create fear by the way you talk to yourself in your mind. You can also created confidence. Stop playing scares. Start getting excited.