I am not a writer, in any language. Nevertheless I can understand what you are saying. Writing something in Greek sounds indeed like another person and since I write thousands of words in English every year but only grocery lists in Greek, I do feel sometimes that my English speaking self prevails over the native speaker. The motto of my first teacher in English was something like "learn to speak English, learn to think English". I remember her every time I want to translate something that I have written from English to Greek. It is almost impossible. It sounds totally not me, so I usually write something else instead.