I get really nervous and can't sleep it usually happens when grades come out or finals i always imagine the worst case scenario i think it's anxiety?

Anxiety: Catastrophic thinking and unconscious exaggeration are couple of thinking patterns associated with anxiety. Mild anxiety responds well to cbt (cognitive behavioral therapy) , but moderate to severe may require medication. See a psychiatrist to evaluate and decide what level and what is the best course of action feel better.

Lets use that: You can really benefit from visualization ace-ing the test -just as easy to do. Visualize yourself from study to good night sleep to up in the am and getting to the test optimally and having an excellent test experience and ultimately ace-ing the test. aUse your brain power to make helpful choices in thought not thought choices that undercut you!!-Best Wishes