Refused assessment and don't want another fight

This is probably going to be a long one, but I will try and keep it brief.

Our 15 year old daughter is autistic.  We know it.  She knows it.  Everyone who meets her knows it.  We have not needed to get an official diagnosis because it wasn't necessary due to us home educating and all her needs in that area being met.  However, college and post-16 education is looming (Sept 2025) so the GP agreed to support a referral for assessment because we all know how long it can take.  I provided a letter detailing her challenges from a very young age until now (much more detailed than any school would have provided according to a SEN teacher friend who proofread it), I provided a copy of the AQ10 (she scores 10/10), I provided copies of boxes 2-4 from the NICE guidelines detailing her challenges from when she was the preschool age, primary age and now of secondary age, but apparently the referral does not contain all the information that is required.  What is that information I hear you cry?  We do not have an EHA and have not attended a parenting course.  It has taken me a year to psych myself up and request the referral and it has instantly been denied.  I have tried to speak to the organisation that is responsible for screening referrals, but I can't get through on the phone (apparently busy with other calls) and I have had no response from an email, not even an acknowledgement that it has arrived.

We have fought for almost all her life to get things into place.  She is sight impaired (late diagnosis due to negligence of the hospital).  She needed training on how to use a long cane and had to undergo a social care assessment for that to be funded, only to have the LA refuse to continue funding the training against Guide Dogs' recommendation.  We ended up going all the way to the LGO with our complaint and it took two years to still not get anywhere.  She has been refused an EHCP because she is basically not blind enough and I didn't have the strength of resolve to fight that one (thanks covid).

She also has a condition called chiari malformation with an associated syrinx and getting an agreement on the best care plan for that was hard work.  Thankfully she now has a great neurosurgeon and we are very happy with his plan.

And now this!  I know we need to fight this to give her the best opportunity to thrive when she goes to college, but I am utterly exhausted already.  I just don't know what we are supposed to do or where we go now.