It is possible for a Yorkie to have a liver shunt that goes undetected for years and causes no outward symptoms. One of LadyJane's Yorkies went through this:
http://www.yorkietalk.com/forums/sic...ver-shunt.html
Head pressing, running into things, and pawing at the face are concerning. Have you discussed this with your vet? I would do a thorough physical, checking eyes and teeth, along with blood tests to cover the liver.