My university gave me the equivalent of 2 years of credits (officially starting me as a junior) for the 6 AP tests I passed. But my BS still took 4 years.
What kind of college only requires three classes per year? My understanding (as someone who has received college credit for AP tests and subsequently graduated) is that a single AP test takes the place of a single class - usually three or four credit hours. You were a junior with only 24 credit hours to your name?