overloading is doing more than the usual load in a semester. e.g. most unis you do 4 subjects (of some unit of credit value). Overloading would be doing 5 subjects.
just enjoy your 3 years of study...
uni > work
and not sure if u can do 3 to 2 years...even if you can overload each semester and do summer courses, your 3rd year courses should have 2nd year prerequisites.
Even 2.5 years could be tricky.
For example, if for your major u need to do a particular 3rd year course thats only offered in 2nd semester which has a 2nd year course prerequisite that's only offered in 2nd semester too and that 2nd year course has 1st year prereq too...etc. I know if you wanna major in pure mathematics at UNSW then thats the case, not sure about different commerce majors.
You seriously don't want to overload every semester. It will drive you insane. You'll pay the same fees, live with 25% more stress than everyone else, and probably suffer in your marks/social life/everything just so you can graduate a semester early. Just remember what everyone always told you about uni being the best time of your life.