Short of attaching a vid can you describe more precisely?
I’m having trouble imagining what „too much rotation“ might be – As long as you do not end up on your back…!!

First thing that comes to my mind - perhaps engaging core-butt muscles will help.

Usually ppl rotate too little.
TI emphasizes full rotation to “side swimming” – at least during drills.
Then, in full stroke, you don’t go as far.

Or is it a balance issue?
Perhaps do practice the simple balance drill with rotation from one side to the other so you find your balance when swimming on your side, then start skate and zipper swimming.