I would recommend OT that specifically investigates sensory issues if your DC has issues with labels or texture of clothes, seams in socks, food textures, sound, light as well as balance, difficulties learning to ride a bike etc. DS1 was assessed using SIPT. Will have to go private but well worth it.
DS1 also saw a behavioural optometrist in the NHS that also tested for retained reflexes which can contribute to anxiety - the body is constantly in a high state of alert due to emotional and sensory disregulation leading to a low tolerance for stress, hypersensitivity and fear of change. DS1 had several retained reflexes and we followed an exercise plan. Worth googling.
But for all we could do at home, the school played a huge role. DS1 was selectively mute at school but parents were never informed. We only found out when a teacher was present after school in a classroom where DS1 was talking 19 to the dozen proudly showing us his work and was taken aback because she had never heard him speak. He had been a pupil at the school for years.
It is very difficult to get support for a child that freezes (internalises stress) rather than fights (externalises stress) in school. But displays severe anxiety before and after school.
DS1 was not diagnosed as autistic (private assessment) and also had private EP, OT and SALT assessment until transition to secondary loomed. Transition failed, DS was out of school and we went to tribunal. Tribunal ordered specialist private school but he only managed to attend 5 terms. After SOS!SEN threat of JR he had tutors at home for 5 GCSEs plus SALT, OT and private therapy and NHS provided weekly visits from youth mental health workers. But all support ended when he became an adult - sooner because of Covid.
DS1 is now 24 and has been housebound for years only leaving the house when I drive him to a private dog field (we do have a dog) where no social contact is guaranteed. He locks himself in his room when trades people come to the house. Needless to say I am his full time carer.
Maybe it was always going to turn out this way. Maybe if he was diagnosed earlier he may have had more support and understanding. But that means that schools have to be willing to support non-disruptive DC that are meeting educational expectations for their long term wellbeing and mental health.
At present it seems that the SEN budget is spent for the benefit of schools to provide additional teaching to pupils not meeting expectation in tick box assessment of school performance or are disruptive due to not fitting in with current teaching policies and staffing ratios (or are undiagnosed waiting for school evidence and referral and long waiting lists) rather than using the SEN budget to support DC who they know have a life long potentially disabling condition and those being assessed or awaiting assessment.
OP is a case in point. The needs of her DD are overlooked in favour of DC prioritised by the school based on the need of the school rather than DC. If all these DC have EHCPs and this is the school’s priority then she needs assessment for an EHCP.
Diagnosis should not be needed for support but the report will often provide advice to teaching staff. The previous school can’t refuse to give information once a SAR is made. It is a legal obligation.
OP you have sufficient information to request assessment. This starts a legal process where you have right of appeal and the school and LA will have to collect evidence to prove that assessment is not necessary. Or that assessment shows an EHCP is not necessary or that an inadequate EHCP meets need. Once the process is started you have the ability to present further evidence as it becomes available through SAR and private EP, SALT and OT reports.
Given that your DD is 2e it may be a good idea for the EP to conduct WISC and WIAT which assess cognitive potential and actual academic performance. With a child who scored highly on standard IQ tests (I think DS was around 146) but only scores average or below average on performance then comparative scores may be statistically relevant in terms of EHCP assessment - ie less than 2% of those with the same cognitive ability would have the same performance scores.
Once you apply for assessment be prepared that the school will stop giving lip service to being on your side (whilst doing nothing, not doing what they promised and ignoring your emails) and will be on the side of the LA collecting evidence that DD doesn’t need an EHCP.