I've tried everything. She won't talk to me. We've always had a really open relationship despite her behavioural problems until we moved house around 7 months ago to the other side of town.
She still attends the same school, she still gets to spend time with her friends etc, I've extended her curfew to allow for the journey time.
She has Autistic traits. She HATES change. We had no choice but to move where we have, we had outgrown our housing association house years before AND due to my disabilities I needed an adapted house, a LARGE adapted house (DC's also have disabilities). There was ONE suitable HA house in my entire town. Old house not adapted and unsuitable for needs.
She also fell out with her long term BFF's, a set of twins, when she was 'Wendied' by a new girl in the school about 4 months ago. (Hopefully you know what I mean). She lost her other BFF to acute myeloid leukaemia just under 2 years ago.
She last properly 'spoke' to me three days ago, but it was only to ask a question about periods. (No she's not pg, she's on right now, though it is a worry despite many many talks as she is severely needle phobic - teachers had to hold her with me to get her HPV done - AND she has never been able to swallow even the smallest of pills, so all she uses for contraception is condoms)
This was ok when she had a long-term boyfriend (they would both talk to me in a grown up manner about it he was around 6 months younger than DD but had no parents was in a children's home...) but they started being a bit on and off from August and split up on Christmas Day. Since then, DD has just spiralled into lots of week-long 'relationships' with god knows who, all I get are first names, and have to guess from looking at her fb friends. Her other boyfriend she had been with for 18 months.
Her dad, not knowing her that well, (long boring story to do with him only working out how to be a grown up when his third DC, his second with DD's SM, was born, by which point DD was 12yo...) got her a blackberry for Christmas, which I am unhappy with as she is chatting to God knows who on BBM, tbh I'm glad I've had reason to get her off the damn thing for a bit.
So, to recap :
DD's BFF dies of leukaemia.
We move house, a terrible event for those with Autism or Autistic traits.
DD struggles more with GCSE schoolwork
DD's relationship with her Boyfriend gets rocky - suspect him cheating.
DD self harms for a month, gets referred for counselling.
DD's other BFF's get a new friend who ostracises DD from the group.
DD starts hanging around with her boyfriend's mates, who ARE a bad influence (think many minor convictions for Criminal damage, breaking and entering, GBH...these are all 14-17yo's!)
DD and boyfriend split up, DD has lots of 'flings' did speak about self worth and STI's.
DD gets back with boyfriend.
DD finally gets sone counselling in school from a charity.
DD's behaviour gets worse, am at breaking point, so she goes to her Dad & SM's over the Christmas hols, hastily arranged before I kill her or leave home myself.
DD's boyfriend breaks up with her by text (bastard) while she's 600 miles away at her dad's, and has the fucking temerity to tell DD that he has feelings for DD's new 'BFF'.
DD comes back from her Dad & SM's, and all SEEMS much calmer.
DD seeing someone new, but looking at fb it seems she is also seeing around 4-5 other boys too. 
DD refuses to talk to me any more.
DD suddenly decides 2 days ago that she will do what she wants, when she wants, and I can't stop her...
So LOTS of bleurgh!
Yesterday when I had to take her to school, I saw her LSA who told me DD was struggling with a bad case of exam stress (why not tell me sooner?!).
Yesterday, on pressing, DD wants to drop Health & Social care as she is getting 'U' across every topic and is finding it too hard.
I agreed as there's now no way she can get anything but a 'U' grade, and she could use that tine in the LS base to work on other subjects she is struggling with like Maths.
Today I got letter about her needing to resit Core science.
Anyone know where to start?!