Trying to tell if I should change my alternator

About 3 weeks ago my battery light came on in my van and some other dash lights flickered a couple times. I left town for about a week and when I came back my battery light stayed on what seemed indefinitely. I charged the battery (which was at 60%) completely on a trickle charge. Drove for a week and the battery light kept coming on and off throughout it. So I started diagnosing what I could.

Took it to autozone for them to check the battery and alternator which they were unable to do cause the battery was again at low capacity. So I bought a new battery and put it in (the old one was 6 years old). Returned to Autozone for them to check the alternator and this time they told me it was fine. During this whole time the battery light continued to come on and off at undetermined time.

Today as I drove to work all the dash lights flashed then shut-off and the car stuttered before picking up and continuing. I figured it had to be the alternator so I bought a multimeter to check the alternator voltage hoping for a clear answer. This is what I found.

Battery - 12.8V
1st Alternator Test (Idle) - 16.2V
2nd Alternator Test (Load - A/C/headlights) - 14.5V
3rd Alternator Test (Idle) - 15.2V
4th Alternator Test (After Short drive) - 14.8V

What do I do now, instinct says get an alternator cause its probably the voltage regulator but that stupid alternator is $220.

Thanks
Sheldon