Is she currently on steroids? If so, steroids will cause a marked increase in water consumption (short explanation: this is the body's response in attempting to dilute the steroid-induced increased sugar concentration in the blood) which causes a spillover effect - quite literally - in the form of excess urination. Something to consider when looking at her potty schedule.
I agree with changing diet and trying to get her allergies under control without the use of steroids. Not healthy at all.
Yorkies can by trying little things
Good luck.