Forgot to ask something important.
How bad are your symptoms? Do those antihisatmines help you?
When you say you have to rely on nasal spray, what sort of nasal sprays? Cortisone or decongestant?
If you using decongestant ones, it's very bad and you shoud not user it more than 3 days. Cortison sprays like rhinocort are not very good for very long term, but if it helps you, it's ok to use it for a while.
I have been diagnosed with the exact same alleries, but I figured out that it's not the main cause, it's more jut an additional thing which make it worse.
The real problem is the humidity and probably the air pressure. (it's just my guess and findings from my experience)
There are three things which can cause the congestion in your nose:
- mucus:easy to clear with saline and antihistamines. but if you blow your noseand nothing comes out, it's not mucus
-swollen turbinates. Could be inferior or middle or both. There's a surgery for it, I had it done, they shrinked my middle one but didin't help not one bit. Saying that however doen't mean that it won't help others, but there's a risk in it, you can end up with an uncurable ENS (empty nose syndrome) Thanks god, I'm ok, but my surgery did nothing at all exept costing me a fortune.
swollen blood vessels:
it an be shrinked with blood vessel constrictors, like pseudoeffedrine, the problem with it, that it's not a long term meg, and makes your heart speed up so won't be able to sleep, like strong coffee effect I guess.
My guess is that when the weather gets humid, rainy, low air pressure, your turbinates and blood vessels swell up.
For permanent cure I suppose is getting away from that climate. But give a try with all the other thing I and other here mentioned and keep in mind that you can be most likley cured just by moving away
let me know how you go, good luck!