Hi Roundabout,
What strikes me most about this is that your DD's emotional, health and educational needs are not being met (whether 'perceived' or not, she feels judged by those caring for her at school), simple instructions are not taken seriously enough to be followed and she is (I presume) being left uneducated by the school whilst she is too poorly to attend.
Although your DD's school are on the face of it 'working with you' at the moment, it doesn't seem like enough is being done to ensure she is still being educated. Has the school put you in touch with the local Special Educational Needs Co-Ordinator yet? (the special educational need being that she is often too poorly to attend school)
I would suggest you make contact with your Local Education Authority too, they will most likely put you in touch with an Education Officer. The Local Education Authority has a legal responsibility (oddly the responsibility lies with the EA not the school) to ensure every child in their area receives an adequate level of education, it is the Education Officers role to advise the parents and school of how the Education Authority can best meet the needs (they can also unlock funds to help support needs). If it is a small school they may not be aware of what support is available.
I was a very poorly child I missed a lot of education due to long stays in hospital - sadly those gaps were never filled, I spent my whole school life feeling like a failure because I was always running to catch up with my peers - I failed secondary school and my teachers would always report 'Cat has so much potential, if only she would concentrate...' it wasn't the concentration, it was little things like I didn't know the formula, so would spent a large part of the lesson trying to work out how to make the sums work (for instance).
Education is so very important. There are means to help your DD catch up at home or in other environments that allow her illness to be accommodated for, with adults who understand that DD may need a nap or her eyes can't read today so they will change the lesson plan.
Feeling stressed about school will not help DD get better, but missing it will have a marked impact on her future - it is the EA's responsibility to find a solution that works for her - but you will need to push them and keep pushing (funds are short).
I hope things get better for you both soon.
Mrs RC