Have you checked with your pump company for clips? They usually have several options in clips/holsters. My 15 yo has been on the pump since he was 8. He started wearing it at about the hipbone location attached to his belt or wasteband of his pants. Now he likes to wear it on the back of his wasteband (which I would think is painful when leaning back in a chair) with his shirt over it.
For women, I know some do wasteband. If I remember correctly, there are some soft straps that attach to the bra or act as a garter-type thing for a more hidden option.