As writers, we are often hard on ourselves. Despite our talent, we tend to feel unworthy and insecure about our writing. We compare ourselves to the great masters and think that we will never be as good as them.
Relax, you are normal. Most creatives have those feelings, including the great masters. It's part of the process of creating, and the trick is to accept it and write anyway.
Let your voice do the writing instead of those feelings. The moment you do, they evaporate, and you regain self-confidence.
Having said that, it's sometimes a good idea to remind yourself how great a writer you are. One of the best ways of doing it is this: