twenty-one days is a natural stopping point, beyond which you will enter a deeper level, and you might not be quite ready for more. only you can honestly know where you are at, based on what you did before the fast, and what condition you are in.
as it is the lunar new year today you are probably feeling stirrings to do something different. personally, i feel 21 days is a very respectable length of water fast. i don't know your history...
as for myself, i worked up from a few days, to my first longer (29 days) water fast, and the last week of that one was hard. Twenty-one days was easier. even then, i think we tend to get too concerned with refeeding too quickly. we could probably all go much slower with that.
Ah yes, even the smell of your own body, can be discerned, from your own breath, let alone others.
if you feel up to it, you might rest and simply not drink for some hours and see if that brings back a sense of wanting or tolerating water. but be very mindful of resting, and not getting up too fast. try boiled hot water, to sip; that change too can help some people. i couldn't drink anything but boiled hot water after a couple weeks.
let us know anything further, any more details that are relevant. . . it might also be a sign that you ought to ease out of the fast. Ease is the important thing. you would do this best with some very diluted juice that appeals to you. maybe orange, half water. only small amounts.
rest a bit, and see if you can tune in honestly to what is the best course for you. having the idea of going forty days on water can be like biting off too much, maybe. if i didn't feel i could stomach water, i simply wouldn't. for some hours. . .
I might also see if i could have someone get me something good, beautiful to smell. maybe an organic orange or lemon, or some flowers, or essential oil.
These days, i wouldn't Water Fast without thinking of these things, as important adjuncts. what might have worked for Jesus is not quite what we are facing these days, with the levels of physical and environmental toxicity.
be gentle and respectful with yourself.
ps, as i told someone else, EFT be wonderful for water fasting. since it works with the meridians, it can shift the body in amazing ways, and of course the mind, the emotions... maybe something to look into for your next fast.