Is my puppy pregnant?

Question
My 9 month old GSD got out of her "invisible fence" the other day when I wasn't looking. She has been in heat for the last 2 weeks and is now going on her third week. My breeder suggested waiting to spay her until 10-12 months, so I did. When she ran away, she was with a white lab. I'm terribly worried that she may be pregnant. What are some signs that I can look for, without taking her to a costly vet?

Answer
There really isn't much telling until they are a month along.  At that time an experienced person such as your breeder may be able to feel the developing puppies.  A vet certainly could or could use X-Rays or ultra sound to be sure.  A vet check now would be a good idea since unplanned breedings can cause both infections and injuries.  

It is a real shame your breeder didn't warn you to be more careful.  Any breeder that suggests delaying past 6 months is an irresponsible idiot if they fail to tell the people to never leave a female in heat outside unattended.  I am afraid many people like you are innocent victims blindsided because you weren't warned of the precautions you need to take.  It upsets me greatly how many similar questions I see here and elsewhere.  Please make sure your breeder knows the problem their neglect lead to.  Remind them that we slaughter millions of dogs a year for lack of homes.  Often ones that lead a short, miserable life.  The science behind delaying spay/neutering is quite thin.

You are now faced with work and expense if she is pregnant.  Whelping a liter, caring for puppies, and finding the right homes for them isn't easy.  At least you haven't waited until the last minute.  You have time to go to the library and borrow a book or 2 on breeding dogs and learn what she needs.  A good place to start is http://www.woodhavenlabs.com/articles.html#breeding

I left out a very important point.  Even though she was bred once, she will still take any chance she gets to breed again.  Doing so will increase the chances of pregnancy, injuries, and infections.  Don't leave her outside unattended for another week or 2.