Good on ya for noting....
You still have a few, maybe a dozen mph left in your tank. You're hitting with spin still, and dead flat would get half that.
Maybe a little jerky on the windup works for you, but do you do that on groundies and overheads? Smooth seems to be in the trait of every fast server.
You have good arm speed and snap, but I wonder if slowing down your motion and setting would give you more precision, so you could go for more big serves???