I am going through the same thing. I made an appointment my little one to get spade and a few days later she goes into heat. I had to put a diaper on as she was spotting pretty heavy for about a week. I now have to wait until the end of May to reschedule her appointment
Major bummer because I want to take her to the dog park which is her absolute favorite place to be. So for now, we just have to settle for walks until I can get her spayed. I keep her away from all dogs and she hates it because running and barking and playing with other dogs is all she want's out of life.