Sex is not 'my' reality. It's just a function of being a species that reproduces sexually.
I can no more say 'agree to disagree' than I could if you wanted us all to organise our lives around the earth being flat.
If your male child said they were female & it upset them & caused them distress if you insisted that they were wrong, would you continue to do it?
I would sincerely hope that they would be able to accept the reality of their sex, as many trans people do.
Or would you try to understand them, avoid causing further upset, keep them safe from harm but also uphold their right to their perception of reality?
You are making trans people sound like people with a schizophrenia diagnosis. If my child had a schizophrenia diagnosis I would do everything I could to protect them from harm, but I wouldn't think they had a right to a different perception of reality - do you really think this right exists?
If I started to say that you have to believe what I do, I would be wrong.
Actually society does function on the basis that we must agree on basic concepts of reality.
Of course I know I have a female body. I am also not female.
That is a logical and linguistic impossibility.