What dance do you do well? Does your son know waltz or fox trot?
The song you have chosen is just too slow to do a fluid Fox Trot. Great song, but not one that is good for the mother-son wedding dance.
If you both know waltz and fox trot fairly well to begin with, just google "mother-son wedding dances" and see what else comes up.
If not, just smile, sway in a slow box step, and enjoy "what a wonderful world" it really is.