Hopefully, you have got a really good recommendation, for a vet, from a knowledgeable person. Doing a good crop is really an art, not just knowing how to do it.

Vets are not taught how to crop in school (never have been), so it takes one that really wants and knows how to do a proper job. You can contact some show breeders near you for a good vet.
As was stated before, you do not want a lot of bell left. No bell gives you a clean look, as it blends to the side of the face. If the vet says the bell is needed to help the ears stand, then this is not the vet you want. You don't want it too short, as that would give your dog a pitbull look.
I would do some searching for nice appealing crops and take some pictures to the vet. Of course, every crop will look a little different, depending on how the dog holds the ears, the placement of the ears and the head.