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.
If you indeed have female that thing will be much easier if you want to have breeding pair.
Finding female EBR in lfs is really hard. April know how many time I went over to her shop when she has new shipment as I am looking for girl as well. The EBR shipping she received either are all male of too young to sex them.