Hi,
Yes, it's okay. If you want to fill this space you can put a small table there and some decorations or a lamp so you can read in bed.
I don't recommend you sit with your back to your front door. Can you place the sofa at an angle so that you don't have the door behind you? Then you will face either SW or NW which is better than having a door behind you.
Good luck,
Astrid
