Icky,

I know exactly how you feel, I worry about my job performance, it does seem some times no matter how hard I do, it seems not to be good enough, but the most important thing, is to make it feel good to yourself.

You are smart, and you need to worry more about yourself than others. I know, it is easier to say than to do, I have the same problem occasionally. But remember, when all is said and done, you are doing this for yourself, not for that teacher or not for anyone else.

Best of luck...