You're still her DAUGHTER and she's still your MOTHER. It's all natural that she has such concern for you. But, if she is taking it all to the extreme such as getting mad over every little thing that you do, then obviously you have to express your feelings to her. Tell her to get you a cell phone so you can keep connected 24/7, even though she won't really be there. It gives you some space still, even if she would call you 24/7 wanting to know where you are.
She might have had past experiences when she was your age and she doesn't want you to face similar situations so she shelters you.
Take more responsibilities, get good grades in school and show her something that she could be proud of, she might take it as you are growing up to be a mature young woman.
You could also tell an aunt/uncle to talk to her for you, she'd probably listen more to a mature adult rather than her teen daughter.
I hope everything works out for you.
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I'm from Africa, BITCH!