@Donkeykong2019 - I have a 7 year old daughter who, to look at, you wouldn't think has ASD. However, after her Adhd diagnosis, her paediatrician surprised us by saying she wanted to investigate her for ASD as there were a lot of traits there. She has her ADOS screening at the end of the month.
DD2 wouldn't jump out at anyone as autistic, especially in the widely understood sense of the condition. But the more I learn about girls and ASD, the more I can see where she fits perfectly. Her social interactions are dire, even though on the surface she is a very sociable child. She just doesn't maintain connections well at all.
Document everything. Get the SENCO at the school on board and if it helps, put it all in writing to them. DD2 goes into school ahead of her peers and does a job in the classroom - sensory circuits didn't help her at all. It allows her the much needed transition time to settle into the environment.
'reasonable adjustment' is my favourite phrase. I understand your school want to end the coming in and going at a different time. Part of this might be to establish whether it is a system which works for your daughter. Our school regularly have breaks from the routines they put in place so they can assess whether it is something which is worth continuing with or whether they need to put something different in place.
Part of the assessment process now seems to be putting parents on courses to improve parenting. Some people seem to really take offence at being told their parenting is lacking but there are a large number of children for whom this is the case. I admit, I was a bit put out when I was first told I 'had' to do X course or Y course. I felt relief when in discussion course leaders would tell me that if my child was behaving like A or B then it's not something that course would help with. I began treating them as a box ticking exercise until I was recommended one specifically for parenting children with additional needs. The laughable thing was I, as with the other parents on the course, were already doing many of the things recommended. But completing the course gave us a certificate we could show to prove we were taking an active part in trying to help our children. That course - stepping stones - is a door opener in our area for access to further help.
Once we had got all those out of the way, and had moved to an infinitely more supportive school, we started getting somewhere. But it has taken a very long time. We first raised concerns about our son when he was a year old, possibly even younger. But it took until he was nearly 8 to get a diagnosis which we call a 'working' diagnosis. We know there is more to it and now he is medicated for Adhd, his asd traits are coming out big time and school have referred him again for autism screening.
So don't give up. But understand that it really isn't an easy or quick process. Especially where girls are concerned. My best friend from school only got her ASD diagnosis as an adult in her mid 30's. Even though when we look back to our childhood, the signs were glaringly obvious.