Am I being impatient?

I have a year+ old female and a 9 month old male who have been together since he was about 3 months old. My female is pretty dominant so introducing them took some time, but now they eat and sleep together. I know male chinchillas sexually mature faster than females, and I was hoping by now they would have TRIED to breed. But I have not heard them (they are in my room), noticed any plugs or excessive hair in cage, nothing that would lead me to believe they have bred. I am constantly rubbing on my female's belly, as she loves belly rubs, and feel no change. Am I being impatient, or should I not expect these 2 to ever breed? I am fine with that if that is the case, but I would have thought by now they would have tried. Thanks in advanced for your replies!