I've had sinus surgery and tried all sorts of antibiotics, but nothing seems to help. I'm not very congested, but can feel pressure in my sinuses and get painful sinus headaches nearly every day. There are a variety of things that I have heard from other people who've had similar problems. Maybe you've tried them and maybe not. Cranial sacral adjustments can really shift things around.
Acupuncture can be really helpful.
And you can learn acupressure or shiatsu points that you can push yourself. In addition, I would probably use in your situation some herbs to help my body deal better with infections. There are a lot you could try, though I wouldn't take them all at once. Find out about usnea. Or try hyssop.