This is the basic recipe I use: https://www.reddit.com/r/kombucha/wiki/how_to_start#wiki_mas...
For more information, The Big Book of Kombucha will have everything you need and more.
Have fun! :)
https://www.youbrewkombucha.com/scoby-care-hotel
(Just passing by; I have no personal interest in kombucha, was simply unaware of the term.)
Also, try placing the bottle in a container or bowl, then hold another (slightly narrower container) over the top of the bottle. You should be able to catch all of the liquid in the bowl to pour into a glass.
If you added a bunch of sugar and/or flavoring into the secondary fermentation / bottles, you added too much. If you didn't add anything, then you didn't let the primary fermentation go long enough.