Tabuk, your idea of having her use the dildo is great...

In fact, you might have her masturbate for you. You can get comfy and order her to get naked, lie down, and touch herself. You just watch, enjoy, and perhaps guide her--tell her to squeeze her breasts, or to open up her pussy lips. But if she can bring herself to orgasm, just watch how she does it.

Also, this should put you both in a good D/s mindset. She'll be vulnerable and maybe a little embarrassed, and getting turned on by obeying you; you'll be enjoying her performance without having to give anything back (for the moment).

Woo hoo!