Move On Out Brother
If you haven't already done it
In your room install a draught excluder around your door
D profile soft rubber draught excluder
E profile soft rubber draught excluder
V profile - This ones for finer crevices
Then theres the rolls or foam pads which slide neatly under the door and stay with it whether its open or closed
If your door frame is even and your door is even and all the surfaces are smooth clean and dry, you should be able to put a seal that works great in under a couple of hours tops.
best to measure the gaps around the door before you go buying draught excluders.
If you can afford it check out the classifieds for a handyman who is good at this.
In your room keep your window ajar and your radiator at a much lower temperature than the rest of the house.
This will keep the (clean) air in your room at a higher pressure than the air in the rest of the property.
Air Filters
If you can afford a hospital grade air filter you can afford to move out
If you can't okay. Get a good one. Replacing Filters probably won't be cheap.
If you have a well constructed air tight eal you won't need to run the filter so much.
Cook. Cooking is an inclusive, positive way to fill the property with good smells.
Bake some wholewheat bread (ridiculously easy) The smell of fresh bread is a great smell. Cook / Bake things with cumin rosemary chicken lemon and don't burn it.
Increase your vitamin c intake - and your vitamin b intake - and the amount of veg you take in.
Talk to your mom about electronic ciggarettes - buy her one for christmas - although... be prepared to duck and roll
You're gonna have your family in your life for a long time make it clear that you like them.
Bro. Your Sister. You Know What You Have To Do Bruv.