I have been making my own and drinking tons of it. I have not gained a pound or felt like I am getting sugar. I ferment mine for seven days at 73.5 degrees, with an additional 2-3 days after bottling, if it lasts that long. Just know that if it tastes like vinegar, it likely has very little sugar left. You are cheating yourself of fizz by trying to reduce sugar. You don't drink the sugar, the scoby and yeasts do, to make CO2 and carbonate your drink. Add the full cup! I do 3/4 cup of white sugar and a tbsp. of organic blackstrap molasses to beef up the scoby.
Caffeine is not a drawback if you are of neanderthal ancestry.
Steak, eggs, potatoes - fruits, nuts, berries and forage. Coconut milk and potent herbs and spices. Tea instead of coffee now and teeny amounts of kelp daily. Let's see how this does! Not really had dairy much, and gut seems better for it.