So - have just banned dd from computer FOREVER, taken her phone off her, told her I expect her to do several hours chores a day as she appears to have no homework... 
She is lazy, moody, dresses like a v messy slapper, outrageously rude to all family and authority figures (but not, of course, to friends), reminds me of my age in every other sentence so makes me feel about 100!, takes no effort over school work, imagines she's going to have a 'career' as a pop star
, makes no effort in any other aspect of her life, leaves crap all over the house...
But apart from that... 
So - I need, clearly, to focus on the positives and get a grip, but finding it hard.
Help me please. 