I relate to everything you say. I am 76, and we had our first child when I was 38. (My wife is much younger.) Now, we have 6 grown children. Even though they are out of the house, I still have the same thoughts you do. Soon, your daughter will leave your home, which will create new trauma for you. But it is clear from the expression on her face that the two of you have done a good job, and that she will always remember and love you.