I think the difference between an ASD diagnosis and no ASD diagnosis can be illustrated by this story:
DD3, aged 8. It's Christmas Jumper day. DD3 has some issues with seams so doesn't have a 'Christmas Jumper' but she does have a couple of jumpers that she can wear and we have some tinsel. I spend 2 hours trying to help her decide what to wear and getting her ready for school.
Eventually, we walk through the school office door at 9.00, with two jumpers, a piece of tinsel and a hairbrush in a plastic bag, and I say "She hasn't had breakfast, her hair isn't brushed, I couldn't get a jumper on her, but we're on time."
Two hours later, I have an answerphone message from the head teacher saying, "You did the right thing. Don't worry. She's wearing the silver jumper, I've done her hair, and we sneaked into the kitchen to steal a chocolate brownie for breakfast."
DD3, aged 16. ASD, ADHD, OCD and PTSD now diagnosed. Goes to an independent special school for children with adverse educational experiences.
Yesterday was Pudsey day. Children could wear pyjamas to school. We had gone out and chosen pyjamas that DD3 liked and could wear in school.
DD3 got the pyjamas on and came to show me them. Then she said "I don't like the change..." I immediately said 'take them off and put your uniform on then. It's not compulsory.' Relieved DD3 changed.
The difference is that I knew that her ASD would make her struggle and I didn't try to persevere with a fruitless task.
When DD3 was 8, I was told she was 'fine', 'highly strung', 'sensory', etc.
Now we know she was masking all her difficulties and we were pushing her and pushing her through.
She a smart cookie, a hard worker, a perfectionist. She broke in year 9.