Wow we must have done the exact same thing. I got a 103 as well as guess. Most test are inaccurate because one time I got like a 139.
It also depends on your state of mind when you take the test. If you're exhausted, it will be harder to concentrate. On the other hand, if you have too much energy, you may speed through the test but you may make more mistakes. You have to have the right amount of energy and the right mindset to score well on any test or quiz.
That is, unless you're a self-proclaimed genius, then why spend time on useless information like IQ?