Tonight is the night you stay with her and watch carefully. All that's left is for those nipples point down, and that can happen very quickly. All you can watch now is for more changes in her personality. Also, check just inside the labia, and watch for the color change to very red. At this point she can go very quickly, so watch her like a hawk, especially since you say she's doing some things she doesn't usually do. Separating herself is a good, normal sign, so again, watch her very carefully. Not sure where you live or how cold it is, but now is when I made myself a bed in the barn!!
Praying for a safe and uneventful delivery of a healthy, beautiful little one!!