You have a passion for things to say to your girlfriend
The only thing you have to do really is to determine which would best describe your girlfriend and how much you adore her. The childhood theme name, like teddy bear, is the first category. This is a good place to start since childhood particularly inspires fun and innocence. Toys, cartoon characters you used to watch and other childhood fun stuff are where you can find such cute names. Then there is your memorable times category.