strong-willed child

I have a strong-willed child. Gone is the little girl of the easy-going disposition and light-hearted spirit. Now she is defiant, rebellious, and contrary. She opposes or disagrees with me just to disagree. I already feel like I'm messing this whole thing up and doing everything wrong, and if I don't figure it out soon she's going to be a grown-up disaster and turn her back on God. I hate to sound so dismal, because she's still a sweet girl, and can be so fun, but the fights and showdowns seem to be overshadowing that now. Or maybe just at this moment because bedtime was a nightmare.