Your assumptions are correct: "a native English speaker" - "English speaker" is a compound noun and stays together in this case and native is the adjective describing "English speaker." "a native speaker of English" - The proposition "of" maintains the relationship between the words speaker and English and, again, "native" is the adjective again. "an English native speaker" - This word order indicates that "English" is an adjective in addition to "native" and would be assumed that you are trying to describe "speaker's" nationality. I don't think most people would ever phrase it that way, but this shows that word order is important and it can sometimes alter the meaning.