My Aussi blue heeler would bite everything and anyone often drawing blood. He likes to nip at hands and feet when we are walking by, I was told to have toys out for t=him at all times, then when he bites say 'mine' and pull your hand back and then show him a toy that he can bite and say good boy/good girl when he bites on that. My pup is going on 6 months and now he knows what he can bite and what he cant. It takes patients and some time, but sheperds are smart dogs im sure your little one will learn an acceptable bite from one that isnt.(Also Ive notice with herding dogs.. they need to run, not just walk. My little guy goes for two runs a day and that also lessons the bitting.)Good Luck!
I also forgot to say, that if the dog is very playful and just isnt listening i found a good time out away from you is a good way to teach them that as long as they are biting you, you arent going to play.
You sound just like someone in our puppy class. First you picked a mix breed with a Australian Shep in it?They are genetically nippy.Its what you teach that puppy to do with the mouth thats important. Bite inhibition exercises are a must and "The Nothing In life is for free"training to.Look it up on the net.Is there food bowl aggression?How do you feed?Is the puppy, food motivated?
When I look up into the sky, I think to myself, Wheres the ceiling?