Ok, seriously, you have NO idea how you really did on the test until you get your scores back. I posted the story of my MCAT day on an earlier post, but I think it's appropriate here:
I didn't get to bed until about 3am the night before because my sleep schedule was so off from studying late at night. It was actually pretty terrible because my boyfriend went to bed at 11 with me and fell right asleep and started snoring, so I had to wake him every hour and tell him to shut up. So then we got into a fight and that was a bad idea. Then the next morning, I went to the test center, but forgot my admission ticket, so I had to super-fast ride my bike back to the sorority house to get it. By the time I got back, I was maybe the 10th-to-last person into the testing center, so they put me next to the super-noisy vent that wouldn't be so bad if they didn't keep turning it on and off throughout the day (it groans for about 20 seconds while its being turned on and off). Then during the first section, this kid next to me kept moving around in his seat and making it squeak and kept tap-tap-tapping his pencil. So I spent about seven minutes of test-taking time debating whether or not to tell him to please stop tapping that damn pencil. When I finally asked him to stop, he scowled at me and kept doing it. So that was bad. I had to guess on maybe 4-5 questions at the very end. During the lunch break, I was seriously inches away from canceling my test scores because I thought I had gotten, like, an 8 on the physical science section. But then I decided there was no way in hell I was ever studying for this test again, so I nixed that idea, put my head down and finished the test, even though I was POSITIVE I had done horribly.
And I did fine. The truth is, lots of people don't feel the same on test day as they did during the practice tests. That's because practice tests are less-stressful than the real thing. I'm willing to bet that all those people who achieved or beat their practice-test scores on actual test-day didn't feel like they rocked the test -- I think it's almost impossible to feel that way due to the nature of the test and the test-taking environment. So, seriously, don't psych yourself out before you even know what you got. I bet more than half of you worry-worts will be pleasantly surprised in the end.