Your situation used to be rather common on this forum, but in the last few years word has gotten out about saline irrigation (I think Dr. Oz/Oprah was the tipping point), so it's dropped off considerably.
I invented the most effective saline flush for a chronic infection, but to be honest, I do not know how long you would have to wait after surgery to do it, if ever, so I cannot recommend it to you. I believe your best alternative would be Dr. Murray Grossan's Hydropulse Irrigator, which you can research online, and if you get enough of the infected mucus out of your sinuses, the antibiotics may work better, unless the power and glory of evolution have made the microbes resistant. My journal will at least explain the problem to you, and why the antiobiotics are ineffective with full sinuses.
http://www.medhelp.org/user_journals/show/2322
The main problem, often but not always, is that an infection can lodge in the upper sinuses, and even if your surgeon does an excellent job (which I surmise he or she did 'cause surgeons are awesome), no one is going to do much good work in that area, so the infection can just grow back, and regular sinus irrigation doesn't usually get up there because of gravity.
Do know that it's possible to get rid of a chronic infection like yours. I had one for 5 straight years, and I've managed to have clear sinuses for 5 years. Good luck.