Sorry this is long. Added background details so I don't have to drip feed.
My DD14 is in year 9. She had a terrible year in Y7. Struggled massively with transition and friendships. Began self harm behaviours. This resulted in absences and below 90% attendance for Y7.
Y8 was some absence but more settled. And school was closed a lot due to covid. Received a letter from school at end of Y8 they were monitoring her absence and I could be fined if medical evidence wasn't provided for any further absences.
Now in Y9. DD is under weekly CAMHS for therapy for emotional regulation (she is suspected ADHD).
She has had 3.5 unauthorised days off so far this year due to self harm and one due to very bad period pains.
I have had a a really snotty letter from school. Threatening me with a fine. (She has had 3.5 days off in a six week rolling period) 0.5 was due to being late because her trousers split.
I am a supportive parent of school. I never criticise school. I don't ring in when she can tackle things her self.
DD is very compliant and well behaved, works hard but does lack the emotional resilience of her peers and is often seeking pastoral support
I'm so upset by this letter. Getting her into school is such a battle. I try my absolute best. I'm a working (part time), single parent. She is one of 4, two of which have autism.
I am so angry that I want to write a real strongly worded letter and send photographs of her self harm, which are nasty; (I record it for camh's) along the lines of 'is this the kind of medical evidence you require!!?'
AIBU in expecting them to make allowances because of her needs or just suck it up and pay the fine?
Or am tired at the end of my tether 
(They also spelt her name wrong all the way through the letter, which is a smaller niggle).