She probably is a little on the small side if she is from a hatchery. They do not breed birds per standard and do not care about quality, only quantity. Because they are bred for egg production, you will most likely have a lot of eggs coming your way once she starts. Lucky you 

  Also in your case you could breed her if you wanted to either a LF or bantam. Its totally up to you. I do not have a picture for comparison but maybe someone else can snap a shot for you.  
It sounds like you are getting a good start. I'm sure some people on here will be happy to help you find a pullet for your cockerel. I do think off the top of my head that Sherry Parker has LF sumatras in California.