Do NOT make the mistake of comparing TPR / Kaplan tests with the REAL MCAT!!! The real MCAT is MUCH easier....no, it's not a piece of cake, but I have come to believe that they make those "practice" tests overly hard 1) to make sure people DO take the real test seriously, and thus study harder and 2) to make a bunch of people feel like they absolutely MUST take a review course to pass the real MCAT. Either way, if you're getting anywhere in the mid-20's on the practice tests, you should do SEVERAL points higher on the real thing!
If it makes you feel any better, I got a dismal 18 (yes, EIGHTEEN) on my Kaplan diagnostic. I thought my med-school dreams were over....but I just kept reviewing (read---I did NOT panic) and my real MCAT ended up being a 29. Not a particularly high score...but I ended up being accepted to 3 schools anyway. Just remember, you want to do as well as you can on the MCAT but it is NOT the end-all-be-all of your med-school application! The adcoms DO look at other stuff...and you'd be surprized to learn how very important all that "other" stuff can be!
Good luck...and don't worry! 😀