Since happiness is extremely subjective, how do you objectively measure and assess happiness? Do you ...

The measurement problem is one of the weaknesses of the utilitarian theory. Happiness, enjoyment, and pleasure have both qualitative and quantitative aspects. The quantitative aspects can be measured, albeit, not precisely. For some, money is a good proxy for these quantitative aspects. However, it is the qualitative aspects of personal happiness or utility that are very difficult to measure because they are extremely subjective. Also, for many, the qualitative aspects often exceed or dominate the quantitative aspects  hence the expression that money (a quantitative factor) cannot buy happiness (a qualitative factor).