It's sad OP that you think MN's concern about children being encouraged down the road to transitioning is more about toilets than their health and safety.
No one had suggested that your child has been indoctrinated by school - is there a reason you're jumping to conclusions? How carefully are you monitoring internet usage though? Please be very careful about that, especially if they are on Reddit.
CAHMS are a mess unfortunately - why would you consider any advice reliable from an organisation that suggests splashing water on your face if you feel suicidal? Advising you to reach out to any old support groups is surely a recipe for disaster? If they were going to recommend that surely they would have done some kind of vetting and some kind of way of ensuring the advice was safe and correct and directing you to specific sites? I guess these days it's cheaper and easier just to recommend you find your own online support rather than offer any proper, costly support.
I'm sorry you've been failed OP. Please don't go down the route on mixing up your own hormone cocktails. Watchful waiting is the best approach and not socially transitioning. This from transgendertrend:
There is strong evidence that the majority of children with gender dysphoria will grow out of it and come to feel comfortable with their bodies. All previous published studies show that gender dysphoria naturally resolves for most children by the end of adolescence. However, persistence rates have increased as the practice of socially transitioning children has increased over the past decade. The evidence shows that if adults ‘affirm’ a child as the opposite sex, the child will hold on to that belief for longer. This increases the number of children who want to medically transition with puberty blockers followed by cross-sex hormones and surgeries. These children will become lifelong medical patients, with all the associated and accumulating health risks.
Commonsense, knowledge of child and adolescent development, and existing studies all tell us the same thing: that children grow out of these feelings if we leave them to grow up without undue influence from adults telling them they are ‘transgender’ and facilitating their ‘social transition.’ We don’t yet know how many children in The Trans Youth Project will regret their medical transition in adulthood, but what is clear is that none of them will have the experience of growing up in a healthy, medically undamaged body to compare.
https://www.transgendertrend.com/children-change-minds/