Hi.
What does the 5V source represent?
What does the 14.5V source represent?
Where is the load?
Show me a circuit please with batteries , your actual power source, your actual load.
Sorry, but simulations are like working things out in your mind/brain, put them into practice and find all the things that you didn't think of, wasn't put in the simulation.
When you are looking at uA, even tolerance of components will probably upset calculations.
Tom....... 
oops sorry [soapbox] [/soapbox] (damn got to remember to take the effort to use the soapbox tags.)