I haev a a 3 year old GSD and just wanted to offer words of encouragement!! a GSD, especially a male one, is a very smart dog but one that also will not just accept anyone as authority and will gladly try to become the 'man' of the house -- we learned that quickly and with some consistent training and some rules it is amazing how smart and eager they are to please
its a serious dog that needs serious training/consistency and all should be well -- good luck!!