Also, ask for a copy of your school’s policy in this area? We can probably retrace how it came about/who informed it and figure out how to negotiate it?
You are probably feeling a bit betrayed by the school right now (although I could be projecting how I would feel in your situation!) so get someone (relative or friend) to advocate for you if you prefer.
When I needed help negotiating with school due to conflict around my son’s autism, I got great support from my local branch of Parent Partnership. I have no idea how they approach this particular issue but I would recommend you sound them out. In our case, they attended school meetings as my advocate and got the Education Welfare Officer on my side, much to the surprise of the school.
It’s clear you love your child so try and be a swan and keep a calm, supportive exterior whilst figuring everything else out underneath.
Some people really do suffer from gender dysphoria and it is possible your daughter will be happier as your son, but the current climate makes it very difficult to know one way or the other.
The good thing is that the official NHS (Tavistock and Portland) line seems to be slowly, slowly and always with lots of parental involvement.
The difficulty is that some private routes have sprung up that provide medical transition assistance while on waiting lists for the NHS. This is fine for adults who can be held responsible for their own ‘informed consent’ but not good for parents and children.
There is also a black market route for hormones (although this is easier for MtF people to access, as the drugs are cheaper and easier to administer) so while I don’t want to scare you, it is something to be aware of.
(I’ve been researching a lot of this particular stuff recently because my middle daughter ticks all the boxes that put her at high risk, she’s coming up 12)