With levels from 12 to 16 you have reached the last and highest possible level. Your vocabulary spans at least 5000 words, it is easy to understand anything you hear or read, you can fluently express your opinion both orally and in writing. You can analyze and understand difficult texts, discover textual errors, and your speech is at such a level that you can debate about all but the very specialized topic.
In short, you have the abilities of a native speaker now, congratulations!