Who says she hasn't been traveling back and forth through the rifts for years? Her clothes are in too good a shape to be the ones she disappeared in, and her watch battery still works and those don't last 8 years. She was only missing because she never bothered to contact anyone she knew for 8 years. She could've been doing anything.

I think she wouldn't have contacted Nick now if he hadn't found out about the rifts on his own. She didn't look like she missed him or was longing to be with him, no matter what she said. I think she was just sounding him out to see if his agenda for the rifts was compatible with hers. I don't think it is.