How long did it take to correct your overbite?

I had a full set of braces for 4 years which were removed, then on my bottom and upper right for 3 months now (almost fixed), and he recently told me of my overbite. IMO, he SHOULD have realized it earlier. We're paying out of pocket now and I've had braces for so long. It's going to be so embarassing as a soph plus it'll be my second time with a full set but the overbite is giving me a lisp. He was selected as one of the top dentists of my state, but his STUPID inexperienced assistants are always doing my teeth, so I'm considering a new ortho.