Voltage readings in Transistor used as switch
good questions.  You have the concept down perfectly and you don't have to go to college.  Although it's not a bad idea.  Here is what is going on:

First of all there is a finite amount of leakage current, but it is so small that your meter will not be able to detect it.  Maybe one or two nanoamps, so at 150 ohms, the voltage would be 150 nanovolts (0.15 microvolts or 0.00000015 volts).  Your meter can't see a voltage this small.

As a matter of fact, when you try to read the voltages using your meter, the leakage current from the meter through your leads is probably greater than one nanoamp, so your measurement is affected.  This probably explains why your voltages don't add up.  You could try reading the voltage across a diode by itself with your meter (outside the circuit) as an experiment.

So, as I said, conceptually you have it down.  There is no appreciable leakage current when the transistor is in the off state, but there is always some leakage across any junction that experiences a voltage drop.  So in your circuit, the diode leaks even though the forward voltage has not been reached, and you have (un-measurable) leakage from collector to emitter and from collector to base.