welcome to the forum.
I don't know that I would recommend a same sex adoption. You need to remember that your Luna is very young and dog aggression can develop as she gets closer to maturity (same with the potential adoptee).
Sometimes two females is not a good mix.
This is a great link with lots of great links within about dog tolerance levels, multidog homes, keeping the peace etc. http://www.badrap.org/node/99
edited to add the multi dog link in there is broken - here is the exact page http://www.badrap.org/node/96
you may want to wait until Luna is older to see if she would do well with another dog in the home or chose an older dog to add whose dog tolerance at maturity is known.