I just picked her up today and I am still in Diamond City. I plan on keeping a close watch on this thread just in case I have the same issue. I literally had her for maybe 5 minutes before leaving home in RL.
Have you checked to ensure she isn't overburdened?
"If she is stuck and can't move you might try If your character gets stuck or if your character starts moving slowly when he or she isn’t overburdened with loot, there are a couple of things to try.
One thing I've learned about Bethesda games is to save often and save saves because...glitches and bugs...
I hope it all works out for you.