Fitzgerald has a great point.

I was taking the exams at a Starbucks or at home. I performed best at those locations.

For some reason my lowest test scores after studying (a 610) was taken at a library, the most similar location to a test center.

For some reason the quietness and formal atmosphere affects my test taking ability.

Hi redmark,

First and foremost- you can do it! Don't give up!

The difference between your mock test scores and the actual score could be due to the test anxiety issue. Sometimes during the 'real' test our minds are boggled with questions like 'Will I reach my target score', 'Will I get into my dream school' etc.
If this is the case, I would recommend you to do the following: a few minutes before you start the exam, close your eyes, take the pen and write down on that laminated paper all the thoughts that are boggling your mind at the moment. Then take a deep breath and exhale slowly. Repeat the latter a few times (this helps you to calm down).
Then, hit the 'Start' button and proceed with the exam.

I wish you all the best! You can do it!


P.S. Do this before every mock test you take- just to acquire the habit!