Welcome to Paw-Talk
It sounds like you're rushing things a bit, there's no need to pick her up at this stage. Instead, let her come to you on her own terms. If you need to remove her from the cage, use a container to scoop her up, not your hands.
Remember, too, that exercise balls are not a substitute for out-of-cage time (I personally don't recommend them for degus at all, actually). Make sure you let the degus run around in a degu-proof area like a small bathroom, walk-in closet, hallway, bathtub, etc. As they get tame, they can have more freedom
. Sit with them and let them climb on you, that's the easiest way to bond with degus. Mine always loved to climb into hoodies. You can also offer small treats to speed things along.