It's almost compulsory for authors to suffer from imposter syndrome. We all beat ourselves up over our writing and feel like we don't know what we're doing. Just write for yourself, and take it from there.

You probably have a reader in mind who you are writing for. It's probably someone you know. Have them read it and they will be honest with you. If you don't try to find one, and a group of alpha readers who will be honest and supportive at the same time.