Hello,
As per Vastu Main Bed room should be in South -west only, means if parents are present this room should be occupied by them. Then comes children will be good in North-west position of the House. Thirdly Guest room can be at West position (or) South Position.
South-Wast position Kitchen should be placed will give best results.
Coming to your case, because you doesn't have any option left, You can place your Bed position at South-west corner of that room, and Leave open place at North-East, dont keep any items atleast 4 feet x 4 feet over at North-East corner. If possible shift the door position from North-west to North-East side (or) even shift to exactly center North position which can give better off than present.
If you have more doubts, send E_mail to vanapalli77@gmail.com
V.Ramakrishna.