Jamila, it's really impossible to say how you'll do on the test with this information. You might do really well, even if you haven't taken any literature classes per se; actually, your English class is supposed to be enough for this test.
Why don't you take the practice test in the official SAT subject test book? If you like, we can administer one for you at one of our offices. Just let me know. (You know how to reach me. )
If you don't take the test, nothing happens really happens. You just won't get your money back. It's not like it's going to show up on your transcripts that you chickened out. I mean, people get sick or get stuck in traffic, right? That can't be held against them.