Don't worry, roygush, you really can't conclude much from a Kaplan test.
You can expect roughly five geometry questions on an actual GMAT exam, give or take a few. You'll probably see only one or two probability questions on a typical GMAT, though it's possible to escape without seeing any at all, and you might get three or more on a really strange day. But six? Probably not.
If you got the first 12 right and missed half of the questions from that point forward, you had a really strong test--if you do the same thing on an actual GMAT, your score should be excellent. Just focus on learning as much as you can from the questions you missed on the Kaplan test, and take the score with a grain of salt.