Are you sure they are missing? Since the last time they changed the character login GUI it's not readily apparent. Mouse over either of the Create New Character buttons, it should say you have x character slots remaining.
I personally purchase Bridge officer slot too (thinking it was character) and accidentally bought 2 outfit slot (even I had like 6 to begin with) That is what happen when you buy stuff when you are not totally awake.
I am VERY careful now
Growing old is inevitable. Growing up is optional.