Sounds like you're doing a great job so far and you can't do much better than participating in a puppy obedience class. This is also one of the best ways to start socialization with your puppy.
Be patient and keep introducing your GSD puppy to new things - new people & kids & other animals - new surroundings and from time to time maybe have friends or neighbors drop by for unannounced (to your puppy anyway) brief visits during the week to throw off your usual schedule and get your pup used to accepting change easily.
You're doing a great job - keep it up. Remember - your pup is a baby and needs both mental and physical stimulation.
