A Different Kind of Doctor's Visit

I took my oldest son for a check-up today. All I could remember was carrying him into those little exam rooms as a baby, and consoling his angry scream after a shot. And I can remember when he had to use the stairs to get up on the table. So doesn't he seem almost too big now to be seeing a pediatrician? Is it really normal for an eleven-year-old to weigh more than I did when I got married? Is it right that he is only three inches from being as tall as me? Is he really big enough to get checked out by the doctor without me in the room (his choice, not something the doctor or I pushed for)? When did I become secondary in the conversation about his health? Is it normal that it bothers me that he doesn't flinch, much less cry when he gets a shot? When does he start having to pay the bill?