Its all about responsibility here!
Why are you so anti getting her fixed if you dont want her bred?
Have you thoroughly researched everything you need to know about breeding?
Obviously not or you wouldnt be posting about it here.
When you took on your bitch you took on all the responsibilities that go with her.
You say you dont want her spayed?
WHY????
Look at the animal shelters, the cruelty of man to animals and the suffering these unloved, unwanted, animals go through.
Are you one of these people who dont think it will ever touch you?
If you choose to breed your bitch and that is the only reason she needs to remain in tact, then it will touch you.
You WILL be responsible for every single pup you bring into this world and the wellbeing of your bitch.
Think again.
Your vet is 100% correct.
Get your bitch spayed and let her and yourself live a happier, healthier life.
That way all you will ever be responsible for is her.
You may also like to do a search here and on the internet for the problems associated with having bitches intact and breeding.