Do you ever wonder if your writing is good enough? Is there a little voice that keeps insisting you shouldn't even bother because you don't have the talent or the skills? Do you sometimes think it's some alter ego who is doing the writing?
These are all symptoms of imposter syndrome, which is very real. I find myself re-reading older works and wondering if it was really me who wrote them. I know I did, but the sneaking little voice under my conscious mind says no, you're just an imposter who thinks you can write.
Imposter syndrome isn't an official mental illness, but it is a very real condition. Those who suffer feel that they will be discovered as frauds at any second. It is encouraged by perfectionism and parents who value achievement above almost anything else, but low self-esteem will encourage the syndrome to take root in your mind as well.
How do you combat this demon? Believe those who compliment your work. Say thank you and mean it. This will in turn silence the self-talk niggling at you and reprogram it. It will help you accept that you are capable of attaining your dream of writing well.
When you go back and reread your work, don't tear it apart and give up in despair. Your first draft should be a mess that needs to be trimmed, bolstered, amended, and in some cases completely rewritten. This is a normal process for any writer. Even my best first draft goes through multiple editing passes, loses whole chapters, and gains new passages as work evolves.
So, when that miserable little voice attacks, telling you to give up and that you're the great pretender, kick it out. Pick up your pen and continue. Your ideas and stories are worthwhile, and the only way to get rid of those miserable worries is to keep on writing. A writer is someone who persists, no matter how life stacks up the odds.