If you can afford it, and if you have the tank space, the most reliable method of getting a pair is to buy multiple specimens and wait for them to pair off. I've heard people hypothesize that this method also creates stronger pair bonds - but I don't know if there is any data to support that.
I'm sorry I can't help you with actually sexing your current fish - I've only limited experience with the GBR or EB variant - and I don't believe I ever had them spawn for me.