Dear Annie: I’m struggling badly with something that occurred over a week and a half ago. I’m a mom. My son is 15. I’ve been dating a man for two years now, but I’ve known him for over six. He has no kids and has always expressed his interest in becoming a dad. A year ago, we decided to try for a baby, but I was a bit hesitant considering my son is 15 and I was 35. In my head, that’s kind of old…