Your calculations are correct. But just looking at your data, there should've been a larger temperature change. A change of 3.5 degrees Celsius really isn't a lot. I remember I did this experiment with NaOH and HCl and we had a change of about 20 degrees Celsius.
Did you cover your calorimeter with a lid? Chances are a lot of heat escaped from it into the atmosphere due to the fact that the system is not closed (no lid/ poor insulated cup).