BCBG I second everything you say. I had exactly the same problems with DD1 and I just couldn't walk away, or ask her to go to another room. If I was cooking she would stand there obstinately and continue yelling, if I walked away to another room she would follow me, frequently barricading the door with her body so that I would have had to use unacceptable force should I have attempted to leave, demanding that we "have this out now!" 
She was at a private music school and was constantly in trouble for being late for lessons, not having the right materials, forgetting to hand in coursework/prep, losing coursework/prep etc. right through 6th form. She failed to "achieve her potential" in exams because she just couldn't seem to "pace" herself through them and habitually left papers unfinished.
I lost count of the times I spoke to her tutors/housemistress but always got the same response: because she was such a talented musician there was "obviously" nothing wrong with her coordination so she "couldn't" be dyspraxic. 
After a long illness during upper 6th, which meant she lost more than half her classroom time, she left, having sailed through Music but having only just scraped through one of her other A levels and failed the other two.
She enrolled at a local state 6th form college to retake one A2 and start 3 new AS courses and I went in with her to speak to her tutor about the problems she'd been having. She was tested, found to be dyspraxic, and immediately given extra help with exam technique and they applied for her to have extra time in the exams. She is now definitely "achieving her potential" and to see her developing into such a happy, self-confident young woman just does my heart good! 