Have you tried Superfloss? I recommend the hell out of it.

Here are the two that I have:

This one is the corded one, the main advantage is that you get more power out of it: https://www.amazon.com/gp/product/B0095IMNI0/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

This one is more portable, but the high setting is only about a 7 out of 10 in comparison to the corded one: https://www.amazon.com/gp/product/B000UWAWQU/ref=oh_aui_search_detailpage?ie=UTF8&psc=1