Most Helpful Girl
You don't really need a nickname do you? I don't like them, I never use them with my boyfriend.
Okay, well I sometimes call him love. but that is mainly when I am too tired to think.
I think you could both use nicknames like 'sweetie' 'honey' 'babe' etc on each other, because you shouldn't use that type of nickname in place of an actual name.
If you absolutely need a nickname, I would say go for something personal or funny that relates to your guys' relationship.
Example, if I wanted to call my boyfriend something it would probably be Tater Tot, cause we joke about how he is crunchy on the outside but a softy on the inside. (: