The symptoms that you describe and when you get them is definitely an allergic reaction to something.
You already know that you are allergic to dust so it is also highly likely that you are also allergic to dust mite droppings. Dust mites are not visible to the naked eye.
You may also be allergic to feathers, wool any pets that are in the room. Another problem that can cause allergic symptoms is breathing in mould spores. If there is any black mould on your windowsill the spores from the mould can cause respiratory problems. If you do sleep with a window open there may be grass or tree pollen that come in through the open window.
If you do have mould on any parts of the house inside, you should get rid of this by using commercial products for moulds or wash the area with white vinegar.
If you do have feather filled pillows and duvets and woollen blankets, then change these to polyester or cotton filled items that are also machine washable so that you can wash these from time to time.
To relieve your symptoms you can purchase from your supermarket or pharmacist or by a prescription from your doctor, antihistamine medications and taken them as prescribed by your doctor or the instructions on the packet. Some of these can cause drowsiness, so do have a chat with the pharmacist to help you if you are going to buy them yourself.
A slightly bigger nose is not from having allergies. It is more likely to be genetic, unless you have had a nose injury.
Best wishes.
maybe because you sleep with fan or air condition this happens to me when i sleep with those things. So you could ease up on that and it could improve your condition.