HSO4- ion equilibrium, which side more acidic

I did an experiment in involving the reaction $\ce{HSO4- + H2O -> H3O+ + SO4^{2-}}$. An acid/base indicator was added to the solution. When more $\ce{SO4^{2-}}$ was added to the solution, it turned pinkish red indicating that the acidity has increased, pH lowered. more $\ce{SO4^{2-}}$ should mean a shift to the left, producing more $\ce{HSO4-}$ and $\ce{H2O}$. Based on Ka values, I thought the right side of the equation should be the one to show more acidity and lower pH, but this doesn't seem to be the case. Can someone explain this? 


