Good luck, but don't sweat it. Just don't act surprised when the proctors cut you off 2 or 3 minutes early per section. If you're ready for that, the content of the test shouldn't be a problem by now. And to be honest, if you're testing alright on the practice tests and you've been doing it a while, I don't see any reason you should score under a 160, which should be at least good enough for some decent tier 2 schools.
As far as this being the most important test of your life, are you not expecting to do well? I just graduated law school a few weeks ago, and I can assure you, there is a far more important test looming (oh yea, it's a hell of a lot longer AND harder). I'm not talking about law school exams, if you're like any of the law students I know, you've probably never had trouble in school so this isn't really going to be an exception (unless you let it get to your head).
I'm talking about the infamous Bar Exam, unless of course you live in a state like Wisconsin (where the BAR is much easier) you're going to be studying somewhere between 40 and 80 hours a week for two months to take two (or more) straight days of tests to determine if you can actually use the degree you just spent 3 years and $100,000+ earning. Take a look at the stats on that exam, if you don't pass the first time your chances of failing increase.
So rest assured, you have plenty to look forward to: either you do well enough to go to law school (I can assure you that's a mixed blessing, no matter how much you want it you're going to hate certain aspects of it.) or you do horrible and decide law school isn't for you. But seriously, don't worry about it, I've been a complete slacker my entire life and I've done perfectly fine up until now. You sound like you've done a far superior job studying for the LSAT than I ever did, and most people taking it would have been happy with the score I got.