You are her son and only child, though you're not exactly a kid anymore.
You went through a couple of big changes while growing up, but she's always been supportive.
As a kid, you barely left her side except to go to school and while on play dates. After your dad left, it felt like it was the two of you against the world for a while, like you had to protect each other. It's hard to pinpoint when things changed and you started wanting to spend more and more time on your own or with friends, but you've gotten the sense that the change has been bittersweet for her. She's proud of you, you know that, but you also know she's missed you a lot while you've been gone.