Hi. We have been going through assessment this year as well for DS aged 5.
For our first assessment there was one developmental paed who did a few tests with DS, puzzles, blocks etc and observed him play with his younger sister who went with us. Then she asked us loads of questions about his birth, reaching his milestones, family history etc. It was all pretty straightforward really. Lasted about two hours.
The second time we went there was a child psychologist there as well and she did loads of play with him to see how he was going to use toys. Eg there was a doll and she told him the baby was hungry in order to see if he would pick up the biscuit to feed the baby. Also little figures that she tried to get DS to make up a story with - Good Luck With That! I thought. She had a bubble machine that she showed him and then asked if he wanted a go but held it out of his reach to see if he would point at it. She was trying to get him to use non verbal gestures I think.
Tbh both sessions were like a big long play session and DS really enjoyed them but was tired at the end. It is very draining and I find some of it quite difficult to watch. I was wanting so much for him to do well. I have done a lot of reading about ASD as well so I pretty much knew what she was doing and what they were looking for and when he was confirming ASD traits I could see that so I had to bite my lip a few times not to cry.
Honestly nothing to worry about though. I felt like I talked too much but I am sure the more information they get the better. We go back for diagnosis in October. First appointment was in May, second in July and diagnosis in October so 6 months from start to finish, which seems like a long time but from reading on here I know it isn't. Sorry this has been so long. How old is your ds?