See more on cute things to say to your girlfriend
Childhood inspires innocence and fun, so this is a particularly good place to start. Toys, cartoon characters you used to watch and other childhood fun stuff are where you can find such cute names. Another category is the memorable times category. Now this is easy because you will simply have to remember a particularly lovely time together and take inspiration from there. For example, if you went to the park and she kept looking and touching the flowers, you can call her bumble bee.