First off, don't stress! I know that society, parents, and even peers may pressure you to feel like you NEED to know what you want to do for the rest of your life, but the reality is that interests change, and you don't have to have an answer right now.
My first major in college was criminal justice. I figured out really quickly that I didn't like to memorize law codes, so I changed my major to sports journalism, which then changed to advertising, and eventually changed to PR (Public Relations). The funny part of this, is that now I have a career as a trainer/educator in Social Media (I teach people how to engage and use social media at Dell). My point, is that I changed majors quite a few times, and eventually didn't even go into the field of study of PR. It's not that my degree wasn't important, it's more about the fact that I got the degree.
The other part of this, is that there are many careers out there for you, you just have to think about what you really like, and what makes you happy. I figured out that I like people, I love teaching people, and I love helping. That being said, there are many jobs that fit those requirements. So ask yourself, what is it that's most important to you? Do you like to analyze data? Do you like to help people? Do you like to travel? Think of the things that are most important, and try to find jobs that will allow you to do these things.
Lastly, don't be afraid to change your mind. What you are interested in today, may change tomorrow, or even 5 years from now. Follow your heart, and what you are passionate about at the time, and the rest should fall into place.