I actually teach the Kaplan class and have taken some of the practice tests as well as the real thing. I think you are right on track man.
When it comes to comparing the tests, you will never find one that perfectly emulates the real thing, Kaplan included. The ONLY way to go is to try and improve your knowledge as much as possible and learn good test taking skills. Kaplan, Topscore, Destroyer, Achiever, etc....all great sources, but be sure to learn whatever they are teaching and not focus too much on individual scores.
If you are just at the midterm, I think those are great scores. Most of my students don't score that well. Keep up the hard work and use the practice materials online, they are IMMENSE.