There is a chance that Sasha isn't pregnant - especially if neither of them has had pups before. It might be a while before you can tell though. Gestation in a dog is 2 months - but you might not even see signs until she goes into labor. Bring her to the vet in a few weeks and he may be able to tell you.

I suggest that you get a book on dog pregnancy from the library. (even if you don't think Sasha is pregnant - it doesn't hurt to be prepared!) It'll tell you all about taking care of the mom before pregnancy, during, and how to help mom take care of the pups after. You also should bring Sasha to the vet to make sure everything is okay.

And here's a good article I found if you want to check it out:
"A Little Preparation Can Help Labor Go Smoothly"

I hope everything goes well with Sasha. Get Sabeth fixed ASAP so if Sasha isn't pregnant she won't get pregnant. Good luck! Please let me know how it goes!