Orthodontics

I had orthodontic treatment before, but it didn't work properly, and my mouth became crooked. I'm afraid to do it again because I can't chew food properly. I'm also worried about how it looks aesthetically. I've heard that these days, it can be done in the shortest possible time.

How much can it be shortened? Also, I heard there are orthodontic treatments that are not visible for aesthetic reasons; is that possible?