What does your introversion prevent you from doing? If it's a fear of public speaking, perhaps litigation may not be your thing, but there are other options within the industry. If you're just disinclined to social interaction, you're no less disadvantaged than you would be in any other field. You need to overcome it (to an extent) to develop some necessary skills as a working professional. I'm sure there are plenty of successful introverted lawyers.

If there's another major you think you might prefer, then I think you already know the answer.