The amp gauge is of no consequence. It is just an inline meter to show you how many amps you are using, if it is more than you are producing (bad), or less than you are producing (good). I prefer a voltmeter.
The ballast resisitor is most likely not introducing the correct amount of resistance. I have no clue what a ballast resistor is rated at ohms/watts wise, but more than likely not what is required.
If you are having doubts about what exactly your alternator is doing, just measure the output voltage of your alternator while your car is running (either at the battery, or the output lug of your alternator). Optimally, it should be 14.4....