15 qts is tiny. Have you considered trying something larger with a hide so that she can be as snug as she wants but still have some room to uncoil and move? 15 qts is not really small enough to be a cozy hide and not large enough to be considered an adequately sized enclosure.
Ball pythons go off food sometimes. It's not a big deal, you just have to put up with it. She'll be ready to breed when she's ready.