Good grief.
OP is under no obligation to explain the circumstances as to why she might be asking the question in her OP (but some of you are doing a damned good job of guessing and assuming), or to explain what steps she has taken until now and in what depth to have children, or might take in the future. That isn’t what she asked and none of it is relevant to what she did ask. Not only is it not relevant, it’s unhelpful, insensitive, and/or hurtful.
OP, I hope I haven’t spoken out of turn. I apologise if I have, but some of these replies and questions are just 😱. You have no need to explain yourself.
There’s lots of really useful in here from people who have been where you are, or know people who have.
It’s grief essentially. Grieving the future and the life you thought you’d have at the same time as trying to find and build and appreciate the life you will have instead. I can’t relate to it in this specific circumstance, but in a related one, still to do with children, and all I can tell you from my experience is that over time the sharpness of the pain dulls, the acute constant-ness of it fades gradually, and is replaced by a low-level hum of what could have that’s always there in the background that’s usually drowned out by the other things you build and love around you. In the quiet times you might hear and feel it more. At vulnerable times you might see something or someone that reminds you of what could have been and it’ll be a fresh, sharp thing again for a fleeting second or a bit longer. The hum will oscillate depending on circumstances, but to some degree the hum will always be there. There will always be reminders of what could have been and ‘what ifs’. That way madness lies, but it’s inevitable at first. Eventually you might listen to the hum and smile and look around you and see what you’ve made of your life instead and be pleased with the circumstances life gave you because you wouldn’t have this if things had worked out as planned.