I am not an expert at all, but from what I have seen on this thread, the more/bigger scoby in the bottle, the faster it will eat all the sugar, especially if you are somewhere warm. So if you have 3 scobies in there and also a baby, it is probably eating all the sugar super fast.
I haven't brewed a batch yet though, so hopefully someone with more experience will also answer!
My first scoby has been growing slowly, because winter... I had it in there for a week and barely saw any change, but I came home from a weekend trip to my best friend's and it was starting to film up over the