It may seem inconsiderate of the vet, but we may not know the real reason why they canceled - it could be an emergency at another clinic. Even though stress is bad for Gypsy, if the vet was needed at another clinic to do or read an ultrasound that would save an animal's life, I would be glad to have canceled. I guess working in the medical field, I view things a bit different - appointments get canceled for a variety of reasons, including emergencies in medical people's own families, and they are human and do get sick too.
Hopefully Dawn you will be able to get the testing done soon. How is Gypsy today?