I don't think there is such a thing as "perfection". I didn't start out with perfect teeth, so I know I will never end up with perfect teeth. My mom said a funny thing the other day. I told her my ortho was a perfectionist, and that's why he wouldn't take them off yet. She told me, "Tell him when the rest of you is perfect, you can go for perfect teeth."
I also thought I was happy with mine on an aesthetic/looks basis, but he said he was also fixing it so I would have full chewing function with my front teeth.
As far as your payments go, were you quoted a flat rate, with monthly payments? If so, I'm not sure he would take them off until you're all paid up. Might want to check on that, too.
If I were you (and this is just my opinion), I would stick it out. You're so young. It's best to get this done right the first time, so you're not 44 (like me, YIKES!) with braces.