It's good to see that I'm not the only one who continued seeing a pediatrician well into my teens. I saw mine up to age 18 for my college physical.
While the doctors and nurses at the office mostly seemed to attempt to treat me in an age-appropriate way, there were certain details that proved to be infantilizing.
The nurses weighed and measured me in a separate room (fully clothed except for shoes), but I was instructed to get down to my underwear as soon as I was taken to an exam room.
They were good about allowing me to go back alone without a parent accompanying me, which was nice, but the office had undergone a redecoration when I was around 14. Prior to that, it was very bland -- maybe a medical poster on the wall if you're lucky -- but after the redecoration, I had the pleasure of enjoying choo-choo train wallpaper and teddy bear paper on the exam table.
I saw a few different doctors there, and they all talked to me in an age-appropriate way. I felt mature to be able to answer all of their questions myself, but it felt weird talking about the dangers of drugs and unprotected sex while sitting in my underwear.
Two doctors there did the genital and hernia exams with me standing during my exams there as a teen, which feels more "adult" than the one doctor who always did it with me laying on the exam table (when I was 16 if I remember correctly). But I actually preferred the laying down position. It seemed like it was easier for the doctor, and it always just felt awkward to me to have it done standing.
Only once (at 14) was I asked to lower my underwear myself. Every other time the doctors did it for me, though sometimes they did it in such a way as to minimize how much I was exposed, which seemed considerate.
At the time, I never even really thought about "graduating" to a grown-up doctor. This was my doctor's office, and since they were willing to continue seeing me, it never really occurred to me that I should maybe move on.