Take your car to an autozone, have them hook up the arbst tester to it. Make sure they hook up the amperage lead over your negative battery cable. Then you run the car at 2000 rpm for 10 seconds and at idle for 10 seconds, it will measure voltage and amperage. Then you will know if your alternator is good or not. Also have them test your battery again. Make sure you have clean connections, and check for voltage drops from the battery to the alternator. Check voltage drops from the battery post to the connector clamp, and make sure the battery case is clean. You can loose voltage by having a dirty battery. Take an ohm meter and touch each lead of the battery, then stay grounded and run the positive lead across the battery, check for voltage drop.
That should help you figure out what the problem is. Also is your voltage regulator bad? You have good grounds? Clean ALL corrosion off your battery and cables!!!