Hi Patrick Would suggest getting away from the bird more Will look better with the extra room and might avoid the need for extension tube Are getting lest light
You have a good head angle Would try moving (if possible) while framing to keep rear elements intersect with birds head For focusing try going just past the point of focus the come back and shoot when you hear the beep I trust the sound more than my eyes
btw if you post complete tech info would be easier to see what you are doing The bird could go a little lighter