i had a similar situation.
In preparation for my first test, i pretty much shut out everything and everyone in my life. For several months, my life revolved around my GMAT studies.
i got around a 750 and a 730 on the two GMAT Prep practice tests, then on test day i got a dissapointing 670.
i decided that i had to take the test again, because a 670 was not representative of my true ability. I took 1 month off and then studied pretty intensely for the next month, focusing on SC only.
I went into test number 2 without having looked at any GMAT related material for 3 weeks. I treated the test day as just a regular day. I was extremely confident and even had about 3 drinks the night before.
anyways, i got a 760 the 2nd time around.
If i could do it again, i would slightly modify my prep for the 2nd test.
I would have taken 1 or 2 timed tests during the 3 week period leading up to my test. My timing was way off and I had to randomly guess the last 5 quant and the last 3 verbal questions.
I probably could have gotten a 780 or so...
anyways, given your performance on those practice tests, i am certain that in the near future, you can tell a similar story to the one that i just told.
Good Luck to you!