Hello, I assume from your question that you ate struggling with this 
I don’t know if I am the right person to answer you, because I am childfree by choice (sort-of, I don’t have a partner so nobody to have kids with anyway) and am in my late 30s.
Would it help you to think about what having a child means to you? What makes it something you long for?
It might be about caring, nurturing somebody’s development, feeling loved and valued, contrubuting to society / humanity, finding a group of friends in other mums, feeling you have done the ‘right thing’, belonging, a shared endeavour with your partner, a purpose to your life, comfort in your old age... you get the idea.
Thank your time and be really honest with yourself.
Then see if you can meet some of these needs in other areas of your life? Are there things you can do that will boosst your self worth and happiness as a childfree woman?
I hope this is helpful, and sorry if it isn’t. Sending
xx