It might be easier to just point you to Tesla's JSON API documentation for charging commands and responses:
Tesla Model S JSON API · Apiary
The relevant parameters you'll be looking for are:
1. battery_current (this is the DC current value you're probably already using)
2. charger_actual_current (this is the AC current being drawn from the AC "charger", or EVSE to be more accurate)
If you also plan on implementing a control in your app that would limit the current below the maximum that the EVSE supports, similar to the way the official mobile app from Tesla does it, you may be interested in the variable:
charger_pilot_current
I hope that's enough to get you going. If you want actual API queries and responses from VisibleTesla, I'll have to wait until the next time I do an AC charge at an EVSE to get you samples.