Hi Audrey,
Use this as a guide.
As long as any rooms, garage or extensions that are fully covered and connected through your home, you will need to take them in. For example, if you garage is fully covered and you can go to your garage from inside your home yes you need to include your garage. Take another example, since balcony is not totally covered you need to exclude them.
Take the facing from your front door.
For irregular shapes of house the positions of the flying stars and 8 mansions sectors will alter or shift depending on your floor layout. It will then go by case by case basis and good judgment need to come from experiences.
Cheers,
Peter