I know this is what I'm thinking, so I'm hoping they will have more sessions in time. We see the paediatrician every six months ish, so isn't frequently but then I don't know what else he does except for assess the current situation and refer accordingly, so I guess we don't have any reason to see him more? I don't know. It's probably slightly different in different areas though.
My eldest is diagnosed with an ASD with Asperger's traits, like I am. They explained this as high functioning. I suspect our daughter will be similar, but I think our youngest son is different. He and my eldest at the same ages are worlds away. We didn't have any issues toilet training him, and his speech was fine except for pronouncing certain words. He wasn't behind in any of his milestones so it didn't flag up for us right away. He was fussy with foods from an early age but there wasn't anything else until he was a little older and started to become obsessive with things, then there were issues with sensory things between nursery and infants which started concerns for us.
With our youngest son he hit certain milestones fine, like sitting up, crawling, walking etc. these were all fine, but his speech was the first thing we saw. He wasn't hugely interested in toys or imaginative play and didn't bother with other children. He doesn't currently as well. But our daughter is different, she does enagage in imaginative play for example, which is good. She hit most milestones ok except for speech and was behind with sitting unaided and eating solids (she refused until she was about 8/9 months). However both of them don't communicate efficiently and this leads to other issues like toilet training and understanding danger etc.