Is it normal to still feel really bad 17 days post op sinus surgery?

A pleasant day to you.  Glad to here you are recovering.  No feeling yourself after any sinus or nasal proceedure is not unuual.  Factors that can compound it could be allergies and inflamation.  The extent of your recovery is also determined by the extent of the problem pre-operatively.  Follow your post operative instuctions, and keep your appointments.  Symptoms to consider calling your physician earlier include fever or foul smelling discharge.