You appear to have 16 cores, and the 7% appears to refer to the average load across all of the cores. 16*.07 = 1.08, so on average you are keeping one CPU fully busy, plus a bit more for other things.
Even when you do not have the Parallel Computing Toolbox, MATLAB automatically uses multiple cores for some kinds of computation operations when the amount of data to be processed is "big enough" to make the overhead worth while. Your code either does not use those particular operations, or else your data vectors are not large enough to make it worth starting multiple cores.
Generally speaking, multiple cores will only be used when you write your code in vectorized form, and your arrays are at least 10000 elements (the exact number depends on the kind of operation being done.)
