I'm with you buddy. My Water Fast is also like hell.
You must see that no one can answer your question. We don't know how much toxin you have. People refer to the typical 21 and 30 days because for most people this duration is enough to both remove toxins and then eliminate some excess tissue and heal essential ones in an already clean environment. But these are just typical numbers and everyone is a unique case. Of course all of these can happen in shorter time if someone has less toxins and excess tissue but that isn't the typical scenario with someone who lived the "modern life" for years or decades.
Your cleanse is done when it's done. You will notice it. After that you can decide whether you want to leave your body to repair itself for some time in a clean environment or break the fast. My first Water Fast eliminated the accumulated crap of 3 decades in somewhat more than two weeks.