Some kids just say goodby and leave the kid crying and the teacher calms them.
This is what I had to do. I think when the OP said hers was the only one she was referring to intensity. My DD
was "the only one" as well... sure there were lots of kids who'd cling and cry a bit, but mine was the only one (at our school, preschool, sports, etc... maybe not the only one in the city)
...who turned heads.
Mine was also the only 4 year old who had to arrive 20 minutes before skating lessons so that she could mentally prepare. She had a ritual she had to go through every time, otherwise you couldn't get her on the ice. Once on the ice she was extremely happy and would cry when the lesson was over, but she wouldn't skate unless she had her ritual.
(Meanwhile ALL the other 4 year olds walked in with their parents 5 minutes prior to the start of the lesson and sat obediently as their parents laced them up, and then passively plodded over to their line ups. Not my kid).
One day DH drove us. We left later because we had the car (we typically walk). We arrived with about 7-8 minutes to spare. DD would not go on the ice. SHE HAD TO COMPLETE HER RITUAL (drink some water, walk to the vending machines, try to lace her skates herself, etc etc). Finally we got her on the ice about halfway through, and when the class was over she was distraught because she'd only had about 15 minutes of it. Poor DH felt SO bad.
Yes, I talked to the doctor, yes I asked about OCD, anxiety, spectrum, etc etc. I got nowhere as far as a "diagnosis" is concerned. Sure enough, the doctor was right in that time has helped and she's outgrown most of it (although I don't think she'll ever be truly typical as far as anxiety goes).
I can
completely identify with the OP in that some kids are just really different. I guess I'm stressing this point because I had so many well-meaning parents say "oh, lots of kids are like that," when really and truly, they weren't. I thought I was going crazy! Finally DD's grade 2 teacher told me how atypical and complex DD is, and I want to hug her. Thank you!! It's not just me!!!
(sigh)