I think there can be a very thin line sometimes between different diagnoses. That's why there are so many misdiagnoses of kids. So many ADHD kids who are SPD, etc.

My son's kindergarten teacher was the one who expressed concern because he was still parallel playing and not interacting with the other kids. He was evaluated that summer for autism but he didn't fit enough of the criteria to be on the spectrum. So he shows some tendencies toward autism but he's not all the way there. Once I read the SPD checklist, it just clicked. That fit him.

He was also very behind with his maturity. His hardest years were 5-6-7, and even up to 8. It wasn't until between his 8th and 9th birthdays that his maturity level seemed to catch up to his classmates (at least smaller gap). Then his meltdowns were less frequent and we were starting to see the boy inside. And he made even more progress from the beginning of 3rd grade to the end of 4th grade this year. His teacher said he finally blossomed!

As for playing, the school social worker modeled behavior for him in Kindy, 1st, and 2nd. Showed him how to play with other kids, how to ask to play with another child, etc. Now that he's older, I've found that his weekly social skills group to be the most helpful. How to be a friend, how to behave in certain situations, etc.

My son has a very difficult time with transitions and the unknown. He needs structure and to know what is planned for the day. If there are changes, then there are anxiety attacks and meltdowns.

The memory part does sound like ASD, but it's possible the other elements aren't enough or strong enough to warrant a ASD diagnosis. But go with your gut. It's good that you're getting a second opinion! Let us know how it goes!