How do we apply CO2 sensitivity (3C ± 1.5C for every doubling) to current CO2 levels
You have done multiple things wrong here. One is that you have used a linear interpolation when you should have used a logarithmic interpolation. But that's a different question, one that you have already asked. I'll address that there. That said, a logarithmic interpolation would indicate that the warming due to a 73% increase would be 2.37 °C rather than 2.2 °C.

But that math is incorrect. We have not seen a 73% increase in $\text{CO}_2$ levels over preindustrial times. We have seen a 46.4% increase. The second thing you have done wrong is to incorrectly apply a linear interpolation. The correct value, assuming a linear interpolation is correct, is $\left(\frac{410-280}{560-280}\right)3^{\circ}$, or 1.39 °C.

We have seen more than a 1.39 °C increase from preindustrial times due to the 46.4% increase in $\text{CO}_2$ levels over preindustrial times. The correct math is a logarithmic interpolation: $\log_2\left(1+\frac{410-280}{560-280}\right)3^{\circ}$, or 1.65 °C.

We have not quite seen a 1.65 °C increase. So what's going on? Another thing you have done wrong is to implicitly assume that the current climate represents the steady-state response to the current $\text{CO}_2$ level. It does not.

Climate instead changes rather slowly. Suppose we stopped adding ever more $\text{CO}_2$ to the atmosphere but instead maintained $\text{CO}_2$ at the current level of 410 ppm. Temperatures will continue to rise for quite some time because the climate has not yet reached its steady-state response to the rather sudden rise from 280 ppm $\text{CO}_2$ to the current level of 410 ppm.