Jen, how old are they? Do you ever hear any calling? My males only call in the morning, right at about sunrise (or before) but they both call, and do it every day. My females are 30 - 50% longer than the males and like Brian said are much larger, and more robust. I have the ancon hill morph but the same should hold true for yours. The 2 pics you have seem to indicate the general bodytype of a male and female just as you believe, but unless they are mature, and we can see them together it is a tough call.
I'll see if I can find a pic of a male and female together.