Re: mouthing and jumping
Rameez, 6 classes aren't that much, and the follow up is critical. GSDs take work because they are so smart and so strong-minded. Having a GSD is like having a job -- you need focus and goals, and you have to do it long-term. But it's absolutely fascinating stuff, and they're worth every moment.
If you search on "nipping, jumping" you'll find a lot of people with similar problems, and good advice on dealing with it.
And I do want to say -- the fact that you care enough to seek answers and post here puts you ahead of a lot of dog owners. Keep at it and you'll have a great dog. And a happy one, too -- GSDs really like to know the boundaries and be confident of who is in charge.
It would probably be worth it to see a GOOD trainer (not a PetSmart special, although some of them are good), It's incredible how much you can learn in just an hour, and how helpful it is to have an experienced person evaluate your dog. You don't have to spend megabucks -- even one 1-hour session would be helpful.
You can ask people on this list for someone near you, contact your local shelter and vet for recommendations, and ask a local dog club.
Best of luck.