Is it normal that my mom thinks i hate her?

My mom and I have always had a pretty good relationship. Recently, however, we've been butting heads more often. She does tend to "nag" me about things like cleaning up after myself, which can be annoying at times, but understandable. I am, after all, a sloppy teenager.
Now I'm about to graduate and she's been more relaxed about everything, since I'm about to be off to college within the next couple semesters. I don't think this is the reason, though. Whenever she makes requests, she's very timid about it, while she used to be very firm and punish me if I didn't comply. I feel like I should be elated, but it actually really concerns me. It's as if she's scared of me or something. I'm on birth control, which gives me horrible mood swings if I forget to take it. I can be pretty aggressive at times, and I feel like the things I say can be pretty frightening. I know it's no excuse, but I really don't mean most of what comes out of my mouth at the time. (I've thrown softer things like pillows, and on one occasion I even threatened to run away or lock myself in my room if she kept bugging me. Ridiculous, I know.) I feel like she thinks that I despise her because of the tone I use with her. All of a sudden, I feel as if I'm an abusive mother, and she's a scared little kid. On one occasion, she even told me she thought I hated her.
I really love my mother, and the last thing I'd want is for her to be scared of me. Am I abusing my own mother? Is this normal? How can I let her know that I love her and get her to stop being so scared?
Tl; dr- I've been aggressive with my mom lately, and now she thinks I don't love her. Is it normal?