Teens wants to help mom understand changes in their relationship

How can I get my mother to realize that I'm not a kid anymore and that our relationship has changed? She and I have always been close, but it's different now that I'm a teenager. Some of it's my fault. I get moody, and I know that my behavior hurts her sometimes. I wish she could understand that I'm not trying to offend her or push her away. I'm just figuring things out and going through a lot of stuff in my own mind. What makes it harder is that I don't always understand why I act the way I do. Can you help me?