I would ask your Vet,they would know what to do.
Also you might want to post in the Breeding section,
as I'm sure they have the answers to your questions.
I don't really know anything about Breeding, I wish I could help
you.
Princess acted the same way, a little over a year ago.
I knew she wasn't pregant, that I knew for a fact, but she
sure did act like it. She even took her toys and was moving
them around as if they were her puppies. I had no idea what
was going on. Our Vet said she wanted to be a mommy, so she
had a false pregnancy. She was fine, but I don't think I want
her doing that again.
Good Luck to you, & please keep us posted.