Wtf is her problem?!?!?

i am almost 19 years old - next month. I get good grades - GPA: 3.85. I do everything she asks, so why does she still treat me like a child. I get it, i know she loves me. But lately, she's beginning to irk me again. I recently started driving again because she cancelled my insurance because i am away at college. So i'm relearning how to drive on the freeway, and she does nothing but critisize my driving skills. She's like "You're too close to the car in front of you! You're going too fast! Stop changing lanes!" Everytime she yells at me she makes me even more nervous. I was driving back to my dorm and she started yelling at me again. This time, it was about my studies. She's always encouraging me to spend more time with new friends rather than my two best friends back home. I finally do and she blows up at me. I've been spending a lot of time at my friend's house lately and she said "Don't go over to her house once you move into your new place. You're gonna fail out of school if you do. I can call your landlady at anytime and if you're not there, you're gonna be in a lot of trouble. " I was like wtf?!?!? how dare you! but i didnt say that. I'm so pissed at her. Why is she doing this?! She should be used to not having me at home since i dorm.Everytime i stand up to her, she hits me. I've told her to shut up, and she goes "Say it again, say it again!" WTF is her problem?!?