Hi again,
It sounds like you're doing this right so far. It would help to do a measurement once you get up and running with say a 1 amp power supply to start with.
The op amp draws it's own power plus any output sink current, and anything on the output that sources current will of course draw that from the power supply. So if you run the op amp into a 1k resistor to ground and the max output is 10 volts, the max output current is 10ma so that gets added to the power supply current draw of the op amp itself. If something on the output sources current into the output pin then that current doesnt get added to the op amp, but it does get added to the power supply because whatever is sourcing that current also has to get it from the power supply.
So the total device current for a given device is the quiescent current plus the actual load current. The actual load current is not always the maximum that the device can put out, but is the actual current due to the external elements.