I have seen so many female Bolivian Rams have physical characteristics that had made them appear male ( and vice versa) that I dont take much stock in this as a consistent way to sex. But, with Bolivian females, once mature, you will see a distinctive rounding and reddening of stomach when close to spawn. Also, the dropping of the vent in females.
With German Rams I see more sexual dimorphism between males and females-- especially the dark rams. The males are decidedly larger.
Do you know how old your pair is?