Hello Titanium
Your problem seems to be of substrate inhibition. Consider the following rate equation.
A reaction may obey an equation of the following form
(-rA) = V'*S/(K'm+S+S2/Ki)
in which the constants V', K'm and Ki are used for illustration without any implication of universal or standard definitions. If Ki is large compared with Km the behaviour predicted by Eqn will approximate to that predicted by Michaelis-Menten equation, with V and Km replaced by V' and K'm, in the lower range of substrate concentrations. However, with above Eqn the rate passes through a maximum as the concentration increases, and there is said to be inhibition by substrate, and the constant Ki, which has the dimensions of a concentration, is called the substrate inhibition constant.
As far as solutin is concerned, it beatifully fits your data.
V' = 8.797334, K'm = 21.96526 and Ki = 0.023025
I hope it will be helpful to you.