Combine everything but carrots, celery, salt and pepper in slow cooker and stir to mix. Cook on low for 8-10 hours.Remove chicken with slotted spoon, shred into bite-sized pieces with two forks and return to slow cooker.Put carrots and celery in microwave-safe dish with about â…› cup water. Microwave for 4 minutes. Add carrots and celery to soup .Taste and add salt and pepper as needed.