what modulating testosterone does is increase or decrease the rate at which the ferritin converts to red blood cells. so, if you give your body more testosterone, it should create more red blood cells and leave less ferritin behind; if you reduce testosterone, it should slow the rate of red blood cell production, thereby incresing your iron stores.
it follows that my low ferritin count cannot be explained as a consequence of low testosterone - that i would rather expect the opposite from low testosterone, namely an excess of ferritin.