[cypher]

I don't think you're doing anything wrong, some females do tend to be like this & can never seem to have enough to do!
A larger cage would probably help so she has more to do as well as more space.
Does she have whimzee dog chews? Most hams love those & it may help distract her a bit more, some just enjoy having lots of cardboard to chew too.
Do you get in the playpen with her? It might help to sit in with her & see if she'll enjoy using you as a climbing frame!
Do you scatter feed or use a bowl? Scatter feeding & hiding food in small cardboard parcels or toilet roll treat toys will help keep her busy with natural foraging behaviour.
Cab't think of anything else to suggest but others may have some ideas.