Don't be hard on yourself dangbody... None of us are experts at this - we're all making it up as we go along and not always getting it that right. My parents were strange creatures and my childhood was unhappy... I am certain that it has to be easier to be a parent when you've been given a fantastic model in your own childhood of "how to do it" - not to mention, in lots of cases, on-going support. Many of my friends in their forties are still being parented, loved and supported in umpteen different fabulous ways by their Mums and Dads. I can't think about it too much or I'd cry with jealousy and the injustice of it all. I would love/ have loved a fraction of what they had and still have.
Back to you though - you're getting the most important things right you know - you love your kids and you are thinking carefully about how you parent them because you care very much about getting it as right as you can. That's all you can humanly do.
This board is a great source of advice and information. No-one here is an expert on teenagers... We all WERE, of course, before we had teens of our own and then all your chickens come home to roost!
Don't hesitate to post your dilemmas here often and read about how others are handling the various different situations that teenagers are throwing at their parents.
That "Get out of my life" book is alright, in my opinion, but there may be better ones out there - I've seen "Divas and Doorslammers" recommended and a friend has lent me her copy of "Queen Bees and Wannabees" which was VERY helpful and enlightening - specifically for Mums of girls of this age. It's all about how girls have to fit in with the clique, adopting the dress code, language and rituals that define the group, in order to survive. Might be very appropriate given what's going on at the stable.
Also, you could watch "Mean Girls" with your daughter too - it's based on the book and provides great material to discuss with your teenage daughter.
Hang on in there dangbody...