Tell her how much she means to you. Tell her everything that comes to mind when you see her.
Tell her all the little things you notice about her that she doesn’t even notice herself.
Tell her that when you’re with her, everything is clear but your mind has never been a crazier mess.
Tell her that you’re grateful that she pushes you to be the person you never thought you would be.
If you’re trying to keep her, tell her that.