way2young,
i see where you are coming from.. it's almost like all or nothing/ do or die kind of thing. however, like you said, you are still way too young. 20? what if this works but the effect diminishes around yr4 or 5? this is why it's smart to start with mild (I guess i could say that finasteride is milder than dutasteride, no?) stuff then move up. same with the doses too.
I personally don't think it's too late to switch to finasteride. and see what happens after a yr or so. whatever you do, be consistant and goodluck.