Athenalou,
Even the experienced dont always get it right. You must be so proud of your sons achievements. Stories like yours give other people hope when faced with these cirumstances.
A work colleagues son, wasnt really that tall when he was younger and nothing to indicate that he would be tall. Every time I see him I cant get over his height, I would guess 6'7 he may even be taller, he's about 20.