Where is Sadie peeing?...

We've been worried about not finding pee from Sadie in any of the litter boxes.  It seems she's pretty set on using my tub.  I'm of mixed emotions about that.  I love my bathroom, I hate the thought of her peeing in my beautiful new jet tub.  On the other hand, I hate the thought of her peeing in the hall, by the garage door, on my craft room floor or any other place that might take her fancy.  This behavior increases when she's off the meds.  We'll have to keep a close eye on her.  We hate to re-medicate her, we like her when she's herself, but she obviously has issues that we can't deal with.