Can you describe exactly what you do/use to irrigate? I dunno..maybe something will come to mind
Have you tried looking into a fungal infection as the culprit? It doesn't neccesarily have to be a bacteria. It may be a vague connection I'm making in my head, but since you have such trouble with mold....
And you know what I've noticed today...I started having an all out allergy attack so I thought I'd irrigate to see if it would stop it. Well it did, but there was swelling from the allergy attack and I think that held in water so I felt a bit more stuffy until the Zyrtec kicked in (ran out for a few days, hence the allergy attack). So maybe that's why it doesn't feel like it's helping enough; because the swelling from allergies?
Lastly, I just re-read a post of yours at the beginning of this thread where you listed some meds you've tried. Have you tried Nasocort AQ? Oh..and do you think it would be worth trying maybe half a Zyrtec at a time instead of a whole one? My aunt has to do that and it works for her that way. Anyway..hope you get better soon!