Think about your shared history with your child. His conception, where his sex was determined. All those cells multiplying within you, the mundane magic of growth that happened inside you. The anxiety that it would go wrong, that something would go wrong in this insanely complicated process, the joy and relief when it didn't. That everything grew correctly, everything formed, including his reproductive organs. For a while, you were part male part female. He shed cells when he was inside you, they will still be inside you.
When he was born he came out naked. A naked baby boy. You took it all in with your eyes, you held him close, you smelt him, saw him for the first time, made him promises, maybe shared your milk, you skin flora.
You were caretaker of that body, you got to know it so well over the coming years. Cleaned it, wiped it, held it, smelt it, kissed it better, caught it, carried it, dressed it, strapped it in safely, grabbed a hand before it could run into a road.
The total access to his body, the complete unselfconsciousness, changed over time. And you passed on your knowledge and care to him. All those things you did for him, you taught him to do himself. You taught him to care for that body you grew.
Then he took those skills and ran with it. His own mind whirring and maturing. He made independent decisions, choices, preferences. Behaviour that came out of nowhere. His future more real to him now, his self still a bit of a mystery.
The baby that you grew became a man. Always your son, with you as a Mum, and all those years of shared history are in the past now, where nothing can touch them. They happened, they're real, and no one can change the past. You get to keep them. You get to keep all those memories and all those experiences. They will be written in your body as well as your heart and mind
Because you took such good care, that naked baby that has grown. It's the same body you birthed, the fact you are his Mum is written in his DNA. Nothing happened to it, no tragedy has befallen it, no catastrophic injury or life changing event. Your son is here today, with a body he can uses as he sees fit, to carry him through the world, because of tender care from you and the randomness of chance we all contend with.
Whatever words come out his mouth, however he clothes that body, none of the past changes. None of his sex changes. None of his cells, his history, his DNA, his genetics ticking away inside him. If you want to find your son, the baby you conceived and grew and birthed and raised, just walk straight to his door. He's there. You can touch him, hear his voice, feel his warmth. This is a true gift not every parent has.
Calling him by a different name is hurtful. So hurtful. But this is part of the deal when we raise children, they grow away from us and choose what to reject and what to keep of the things we gave them.
You get to choose what to keep too. You can keep his name inside your head and heart.
We bend ourselves to fit around our children, we play games, we allow decisions we would disagree with, we sometimes let them learn the hard way, they baffle us, they don't accept our experience as worth anything. We let them explore because no one stays a baby forever.
My advice would be to do what you've always done. Care for and protect his body. Prevent him changing it in any way you reasonably can. No hormones or surgery. This isn't for you but a continuation of the same gift you have always been giving him, a healthy body use throughout his life.
However he is baffling you right now, however he is rejecting the things you gave him, stay calm and present for him. Support him by staying connected. Support him by staying you, his loving Mum.
No, you don't have a daughter. You have a son who wants to be referred to as a daughter for reasons you can't understand.
Yes, you had a son, and he is still here. You get to keep all the things that belong to you.
He gets to reject some of the things that belong to him.
The pain in him doing that can be bourne, and overcome.
He came out a naked baby boy. Underneath anything else it's the same body. Still here, the same heart beating in his chest as beat inside you. The same hands and feet that pushed your womb from the inside.
You'll always be his Mum, he'll always be your son.