Give up carbs and sugar. Just do it. I had exactly the same and stopped carbs and sugar for 3 months (basically ate veg and meat, nuts, avocados, but no dairy) and when I went back to the ENT they fell off their chairs. The grade 3 polyps were not even there. They were all set up to get me an operation. Also I couldn't breathe through my nose from the age of 7- constant stuffy nose and snot. Like a continual cold. When I was 23 I had an operation to remove part of my inner nose which was slanty. It did no good at all. Of course the cause of the congestion was DAIRY which I now know (thanks to York Test) I am intolerant to. Give it a go- use dairy substitutes like Koko milk and avoid bread, pasta, rice and potatoes for a few weeks. Note- you may get severe cold like symptoms in the first few days as your nose clears itself out!! It's not a cold- stick with it!