Well, growing up has to happen for everyone. Becoming a separate person isn't easy, but your mom went through it (in her own way).

When you're young, your parents are right. Then you start to develop a sense of self and form your own opinions and make your own decisions. They will not be the same as your mom's.

It's a slow and painful process. If you are ready to stand your ground on what you want, then have a chat with her. Just be ready...don't change your mind. Tell her that this is what YOU want and it's your life.
Get ready for guilt, arguments, and all sorts of mom tricks. It happens.