Experimental difficulty with the iodine clock reaction
The theory is correct. Increasing concentrations increase the number of effective collisions per unit time and the rate increases. So accordingly even in the experiment it should happen like that.

So in visualizing your situation, it must have been an experimental error and  not the theory. (Say there must have been less amount of $\ce{H2O2}$ in the mixture).

In this reaction what happens first is the conversion of $\ce{I-}$ to $\ce{I2}$ (have to add $\ce{H2O2}$). This $\ce{I2}$ will then react with metabisulphite or (even sodium thiosulphate) to produce $\ce{I-}$. Since you have added a constant value of meta in trials 6-10 there is a definite amount of $\ce{I2}$ removed in each trial by meta then the remaining $\ce{I2}$ will react with starch to give the color change.