That sounds very similar to my DS. We ultimately did opt to send him to K this year. I didn't see him going straight to a full day 1st next year without having gone to K. I think he needs the time to get used to the school before having to go full day.
He is a much different kid than he was at preschool. Where he wouldn't participate there he does participate at K. He actually did really really well the first 8-10 weeks but now he is starting to fidget much more. All along he has had a few emotional breakdowns here and there but his teacher is very good with him and has learned some of his triggers. She knows he doesn't transition well so she makes sure to give warnings before group changes.
Before making a decision one way or another definitely check out the school he would go to. Even DS5s preschool teachers said it was so dependent on the K teacher as to how he would do. Also last year in March I was unsure on whether to send him but by summer I was pretty positive sending him was the right choice. So the next few months may just be all he needs.
