Now conventional Flying Star "wisdom" would predict prosperity for a house with 8-8 at the main door. Yet it is not the case here. So much for conventional wisdom.
What is the exact degree of facing?
When you say it is East facing and main door is in the West, you mean that the rear of the house is so much more yang than the front that you feel it is the facing? Can you carefully explain the situation or add photos or even a GoogleEarth location?
Is it a free-standing house, flat, townhouse?
What is outside directly to the NW?
What is outside directly to the West? And to the NE?
What is the youngest daughter's kua?
We need to confirm your measurements. Draw a floorplan to exact scale and place the compass over it so we can see exactly where everything falls.
Don't despair. The situation may not be nearly as bad as you think.
The first thing that jumps out is that the facing is 90 degrees. Any facing in a cardinal direction (90, 180, 270, etc.) the qi is too strong so feng shui is not auspicious. Nothing can be done to change that.
Flats are more complicated than free-standing houses.
And since you are on the 3d floor, I'd put less emphasis on Flying Stars.So your concern about the Stars in the SE can be forgotten
But the good news is that until 2014, the 3d fl is a good floor to be on.
What is the facing of the main entrance to the building?
What sector of the building is the flat in?
Your sister's illnesses: lung/chest problems? Back pain?