If IQ was very important, the top universities would simple do IQ tests to select candidates. The fact that they don't shows that success is more determined by a range of other factors, particularly work ethic. My sister once took an IQ-type test at school that predicted GCSE grades at school. It predicted that she would get a B in French - one of her favourite subjects. In the end, she got 11 A*s at GCSE overall, with a very high A* in French.
Please don't use IQ as an excuse for you not doing well. If you don't do well, it will mainly be because of lack of effort and commitment. Just assume that the test was inaccurate and move on.