If the markings on the side of the film were OK this indicates that processing was OK. If the whole film is blank then it has never been exposed so the film was never wound through the camera. Was it a manual rewind? If so then when rewinding the tension should have ceased on the rewind handle very quickly as it was only rewinding a very small length. What do you recall about the rewind?

If it was an auto rewind then you might have noticed that the rewind time was very short? Do either of these two things I have mentioned ring any bells when you try and recall the rewind procedure?