One of my girls did some of those exact same things. She would take all of the toys she could get her hands on, plus anything else she seemed to deem a puppy (socks, bones, etc.) and pack them in her bed. She was constantly carrying them and shifting them around and whimpering and crying the whole time. She seemed very stressed about it.
We talked to our vet, and decided to take her in. He wanted to make sure she wasn't lactating. You can check yourself before you call by squeezing one of her nipples to see if anything comes out. They stimulate the production of milk by licking their teets (?) and he advised us to wrap her so she couldn't get to them...and take away all of the "babies" and nest items.
I was worried about traumatizing her, but she got over it in about an hour and went back to her normal self. Because she wasn't doing a lot of licking and wasn't lactating much we didn't end up having to wrap her.
Has she already been through a heat cycle? Mine was a rescue so she was almost 10 mos old by the time she was spayed, so she'd had at least one already.
Good luck! I know it's hard to see them like that.
Betsey, who has been lucky enough to live with:
Bruno (7-11-02),Tinkerbell (08-11-11), Chibs (10-2-12)
And at the rainbow bridge,
My sweet Rocky (4/04 to 7/12)