Simple Ohm's Law Question
Ohm's law applies to resistors, not to diodes.  When you place a diode in a simple series circuit like yours, you cannot apply Ohm's law to find the current.

To be clear, if you know the voltage across a resistor, you can calculate the current through using Ohm's law.

If you know the voltage across a LED, you cannot calculate the current through using Ohm's law.

This is because the diode current is an exponential function of the voltage across:

$$I_D = I_S(e^{\frac{V_D}{nV_T}} - 1)$$

So, for example, if you change the voltage across the diode, the change in current will not be proportional, i.e, the ratio of the change in voltage to the change in current is not constant.