@cattia, what kind of imaginative play does your son do? My son is also almost 3, and he seems to prefer to play dress up and pretend to be a superhero, play with invisible stuff (like cooking at an invisible kitchen instead of his actual play kitchen, etc.), or playing sports.
My main concerns are about how he plays. He just really isn't into toys, especially toys that other kids his age like. You always hear about boys loving trains, cars, blocks, etc. and mine just doesn't...he just wants to play sports, or fight the bad guys. He likes to look through books, and be read to, play games like memory and hi ho cherryo. He dumps everything else...blocks, trains, cars, dump and scatter. Play kitchen and food, dump and scatter unless I lead the play. Doesn't like to color. Will play playdoh, gloop and sensory bin with rice or beans...also likes his marble run and musical instruments.
Pediatrician, birth to three, neuropsychologist, developmental psychologist think everything is okay. His speech is great, he takes turns when playing games, very social with us and others...preschool says he does okay with the other kids. He mostly watches before he joins in with play at preschool, they say, and they say he has friends at school.
I just don't understand why I can't trust the experts. The psych and neuropsych are both considered experts in the area of autism, and they don't see anything the matter with his play. They say play is play, and that if he is pretending to be superheroes and playing sports, he is doing fine. He speaks really well, which they also count as a positive.