Since she is now 18 months old and physically mature, you might try a nice long walk or exercise session before you bring her in the house. If she is tired, she should settle down more easily and she may be more receptive to learning the expectation of a house dog rather than a backyard dog.
Sabra - female GSD - born April 30, 2012
Sargeant - rescued senior GSD male/foster failure - approximately ten years old (August 2013)
Max - rescued GSD - Dec 22, 2010 to March 7, 2012 - at the bridge
Sable - rescued GSD - at the bridge