While you are correct in going to another vet.
I have to disagree with two comments made by people
That slightly angers me. My dog is not spayed because we might want to breed her and it's expensive and pointless to spay her really. (she doesn't go outside or get out and she's really small.)
Plus I have a friend of mine who has purebred Whipits and is permitted from fixing any of her dogs because they are show dogs and may be chosen to breed.
AND
neither of my dogs are spayed, there is no need.
THERE is a need to have your dog spayed or nuetered.
You can get cancers, and people's dogs will come around when your dog is in heat. EVEN if you have a high fence OR a kennel. Our sharpei mix came into being when a neighborhood lab climbed a 6 foot fence, then an 8 foot kennel fence to get to her mom, a sharpei.
Also take a look at these reasons, found on a normal web site.

Top Reasons to Spay or Neuter Your Dog or Cat

-Prevents future heat cycles and blood stains on carpet and furniture - Heat cycles or estrus cycles can be messy, by spaying your dog you eliminate this messy cycle.
-No longer attract stray males during heat cycles - Males will no longer be attracted to your female dog or cat after the spay surgery.
-Decreases chances of mammary tumors - If your dog is spayed before the first heat the chances of later developing mammary tumors, or breast cancer, are eliminated and if the surgery is performed before the second heat the chances of later developing mammary tumors are greatly reduced.
-Eliminates the chances of developing a uterine infection - Dogs and cats can develop an infection in their uterus called a pyometra that is life threatening, and in many cases requires emergency surgery to remove the infected uterus. If you spay your pet the risk of developing a pyometra is eliminated.
-Eliminates the chances of developing testicular cancer - When your pet is neutered the testicles are removed eliminating the chances of later developing testicular cancer.