I'm in the same situation (shots for 1.5 years, frequent irrigation). I had sinus surgery, which actually allowed me to get the saline solution into my sinuses (before they were completely blocked), and after about a year the mucus stopped building up. But now I'm still stuck with the pressure.
Are you guys on meds? What kinds?
Also, have you found the pressure and other symptoms are accompanied by any noticeable facial swelling and/or edema-type symptoms?