I don't know how you feel about prongs on a small dog, but they do have small and extra small sizes. And, they really are power steering for dogs; and self correcting. I wouldn't put a prong on a pup under 7 or 8 months old and even then, the pup would need to be "hard tempered." But, your Zoe is old enough.
Some trainers who offer kindegarten obedience classes have the plastic ones with more rounded teeth if you are worried about the chrome kind. And, the chrome kind also have rubber tips that can be placed for a lesser "bite".
I am not negating the need for training, however. Each dog needs individual training and handling for sure.
Its funny, both of my dogs much prefer walking together as opposed to individually now. And, Heidi must have her prong for now, but it is just a training tool and she will transition out of it just like my other dogs who have needed it. She's beginning to master the command "slow" which is nice.