Greetings Mary:
I would be hesitant to suggest that something is amiss seeing that many of our white oak species here on campus are just now breaking dormancy. However, you have been very helpful by providing a history of this particular white oak in that this tree has displayed "symptoms" in the past (i.e., sparse foliage throughout the crown). I wouldn't worry too much about acorn production as fruiting is a cyclical event.
That said, I would encourage you to contact a professional arborist or a local Extension horticulturist to see if they can provide you with an on-site assessment as there are too many variables to consider based on your question.
UI Extension Offices:
http://web.extension.illinois.edu/state/findoffice.html
Illinois Arborist Association:
http://www.illinoisarborist.org/CertifiedArboristsNew.htm