Originally Posted by svenosaurus
I can't swim without kicking.
That is important information. Despite swimming for decades, you are dependent on your kick for balance. Perhaps the reason you have difficulty with the 2bk is that your legs are too busy holding your body up in the water. The way of TI is balance first, then streamlining, then propulsion, in that order. Improve your balance, and it will free up your legs, and your energy, for other things.