Re: yes she is 4......
I think a lot of people who nurse their older children do feel secretive about it. You'd have to be pretty thick-skinned to not let broadly held opinions about a "proper" age of weaning to affect you.
The one person I know IRL who nursed her child through her fourth year doesn't seem to have had any negative outcomes from that- except that the mom did get pretty tired of nursing by the end!
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"