The law states:
If two people of the opposite sex have to sleep in the same room the accommodation will be overcrowded unless the two people are:
* a married or cohabiting couple, or
* at least one occupant is under ten years old.
Even when the youngest reaches 10:
Overcrowding is only allowed if it is:
* due to natural growth (such as a child reaching one of the specified ages
http://england.shelter.org.uk/advice/advice-64 97.cfm
There is no reason why your daughter shouldn't share your bedroom though.