@Imma,
Thank you for reaching out to the community, and I'm sorry for the pain you are going through. While it's very difficult to try and give advice--nobody can know your whole situation, and I know it drives us crazy to have "expert" advice given on our own complicated situation with little context--here is some background and my own thoughts.
I am 48, my wife is 47, and we are parents to a 4 year old boy. My wife wanted kids, but throughout her 20's it was "some time later," she never felt ready. When she was 29, she ran into several types of migraine and persistent headaches; these initially left her bedridden. We did eventually get treatment for them, but the drugs she used all start with "do not take while pregnant." As she eventually learned to deal with the headaches, (she still has them, but much more self regulation / lifestyle management now) we found ourselves at the doorstep of 40, with the typical bad prognosis on fertility.
So, after 3 rounds of IVF, we tried again with a donor egg, and got our miracle. They say a child costs $250k in the US by 18. Well, that would be a bargain, because ours cost $75k before day one! Along the way, though, we had to think through life as older parents: we have more resources, but less energy. And we committed to make sure our son spends time with his geographically-diverse grandparents, as he will have less time with them, then we did with ours.
So, to advice: have you thought about a surrogate mother? This of course would be expensive, but if you are contemplating saving for FI, it might be possible. It might also give meaning to your work--you are on the way to a big goal, rather than just carrying your burden. Now, I list that first to get your attention, but I also have to say there is a lot of other things to really be ready for such a step. First and foremost, are you talking to any kind of counselor to sort out your and your husband's feelings? You do need to be on the same page as this; it is a good thing to be grounded on the realistic possibilities, but this is also clearly a central dream of yours. Other preparation: can you obtain some kind of long-term care insurance, or plan for that phase of your life, if it comes sooner rather than later? (e.g. more savings--include that as an FI spending plan) It is natural and right for you to expect your husband to support your dreams; in return, though, you need to think from his perspective, and the role you are asking him to play in fulfilling your dream. If you can help reduce his future burden, that can be a gift from you to him.
Please forgive the overly-reaching advise of an internet stranger. I hope you find your way, and find peace.