Unless you are writing something literary, why do you want to write complicated sentences? writing is just a means to communicate if you deprive a section of your readers(say non native english speakers) your writing failed!

For the problem of struggling to write but fine with oral communication my suggestion is to just record your thoughts orally on your phone/laptop transcribe them using google docs and than your job would be reduced to editing rather than writing from the scratch which looks easier to me but i can be wrong.