Hi!
Don't worry about your IQ - it's more than adequate! 116, or thereabouts, means you have above average intelligence. Honestly, if you're scoring at 115+, there should be no fundamental issues that block your path to a 700+ score.
By and large, the number of hours you spend preparing is the greatest single indicator of your future success on the GMAT. Sure - there are plenty of exceptions, but for most of us folks, it's all about the hard work.
I'm a MENSA member and it took me three months of very hard work to get to 740 (I started out around 680 when I took my first practice test). Just as having a high IQ is no guarantee of a high GMAT score, a run-of-the-mill IQ does not guarantee you a lower score.
My advice? Put the IQ issue out of your mind. Don't even think about it. Instead, take a practice test, see where you find yourself, and plot out a good strategy to get to 700.