I think I know where LL is coming from, I too think that breeding dogs should be left to register breeders who will test the animals for genetics and health issues (they all have to as per their code of ethics) in fact, I believe they have to give you a lifetime guaranty on the pet. They have been properly trained and educated on proper breeding. Not for "show dogs" but for service dogs, or when you really want that pure breed dog because of its particular personality or characteristics.
Also, just because your dog has a great temperament, it is not for sure their puppies will. We are all here big animal lovers, and the fact that there are so many abandoned dogs because of irresponsible breeding, hurts. It is not a personal attack to your choice.
I don't know if the doctor did wrong or not by spaying her after pregnancy, but I also don't think is unheard off, I did a simple google search and found other cases where it had been done. If you want to be sure, maybe you could contact other doctors, aspca, vet school or vet association in your province, and see if anyone could give you more information on it, then you know if you should change vets...?
Dogs don't need to talk, their life is their message ~ unknown.
"The greatness of a nation and its moral progress can be judged by the way its animals are treated." ~ Mahatma Gandhi