This is how it is defined in the regulations "The dog should be at the handler's left side straight in line with the direction the handler is facing. The area from the dog's head to shoulder is to be in line with the handler's left hip. The dog should be close to, but not crowding, its handler so that the handler has freedom of motion at all times.”
Personally, I try to keep her ear in line with my hip at all times. While it shouldn’t be scored if a dog “floats” in heel position slightly as long as they fit the definition above, I think it makes a prettier picture to be precise.
Glad things are working out for you with the behaviorists.