I’ll add my voice to the whole “Hey, that sounds just like me!” file.
First thing is, stop bulldozing. There’s willpower and then there’s won’tpower. Some of us have enormous won’tpower, and will be able to resist any and all attempts to make us do something that we do not want to do.
You have to find out what she DOES want to do, and be ready to help her in it. But whatever you do, do not take the first thing she admits liking and run away with it. She’ll just shut down even more, and never tell you about what she likes again.
It’s madness, but sometimes the best thing you can do for your child is let them be. That doesn’t mean abandoning her to potential depression and social issues. But it does mean giving her a lot of space.
Have you tried just coming right out and talking to her about why you’re worried? You might be surprised at the results you get when you make the conversation about you, not her, thus avoiding the issue of shunning being the centre of attention.
The only thing worse than raising a teenager is being one.
Remember that she’s in a state of flux. She could change any moment, or never. She might change when she gets to college and finds others on her mental wavelength (I sure did).
That said, I think we need to define the bounds of how worried you should be.
She has friends. That’s good. She texts with them, which seems weird, but is pretty normal for teenagers these days.
Spending all your time in your room with your door shut is also quite normal for teens. They’re making the painful and wobbly transition from child to adult, and so they need a place where they can be alone, sort through their emotions, with no distractions, no demands, and just kind of… find their own level.
She’s getting decent grades. You haven’t mentioned her eating, so I’m assuming it’s normal.
She’s obviously an introvert. That’s not bad, just different than you. She’ll always need a lot of alone time. Accept that, and don’t push.
Above all, relax. Don’t assume you’re doing something wrong… teenagers are complicated and random and it’s never easy. If you relax, chances are she’ll relax, and stop worrying about what you’re going to push her into next, or what question you’ll ask, and she just might open up to you.