Then....maybe I missed something :\
On my Nutrafin, they are literally "fins" running up the inside of the canister.
There are short ones you should just cover with the sugar so you can't see them, and taller ones which show how much water to add.
I'm getting about 1 bubble from my Nutrafin ever 3/4 - 1 sec within 20 minutes of closing the lid using a similar approach to what you're doing. (Note: I switched to using bread machine yeast per an article I read a week or two ago, and it's producing waaay more co2 than the packets included with the original package).