I had the same symptoms as yours for about 8 months and i just had a sinus surgery done. I am not quite sure of what caused the congestion and polyps. But i guess its because of the dust or pollen mold. Recently after the surgery, i have been doing the 'squeeze bottle'- Neti Med everyday and i'm able to breadth freely through my nose and the best of it is that i'm able to sleep well. I'm glad that i got the surgery done :)   P.S - Please dont do the sinus rinse when you have severe congestion. It makes it worse and you might end up with a bad head ache. The reason being, the water does not flow out through the other nose and it might flow towards the eustachian tube in the ears. It is best to use when you feel like your nose is beginning to be stuffy.