Well, I went to an ENT specialist this morning to see if he could find out why I have so much sinus trouble. He did a 3-D CT-scan of my head right there in his office (wouldn't have *that* under socialized medicine!) and discovered that, although my nasal septum appears normal on the outside, as it proceeds further back into my head it suddenly makes a sharp swerve to one side of my nasal cavity, then straightens out to a more normal placement again. Which would explain many of my chronic symptoms.
The ultimate solution is surgery to correct it, but he's not recommending that yet... he wants to try me out on a non-steroidal nasal spray first to see if that helps alleviate the symptoms.