Dude, if 12 is too much this semester, then how is 14 next semester lightening the load?
Well, I'm not sure how other schools are, but at my university, almost every class is 3 hours. So an upper level math class is worth the same amount of credit hours as a low level freshman class. You might end up doing more work (homework, studying, etc) in 1 3 hour math class than you'll do in 2 3 hour freshman classes. So looking at numbers, yeah, you're not lightening the load, but if you take the classes themselves into account, then you can very well be lightening the load with more credit hours.
Last semester, I had 18 hours, which is certainly considered a full load, but that semester was also my first 4.0 in college (ever, actually, never had a 4.0 semester in high school), mainly because I had classes that had less work loads and were easy to me.