Professionals cannot tell someone whether they are TS or not. Professionals can only be guided by a patient's self-reporting. Also, professionals are or should be trained to rule out major conditions other than dressing for sexual gratification, such as bi-polar, depression, etc, that once treated might lessen GID, but even then, professionals are not infallible. Ultimately the only source for answers is within the patients/clients themselves.
Also, we've seen countless threads here, debating what is a TS. Is there a difference between a true TS who cannot be happy without full transition, and someone who can manage a life switching back and forth? Is the first a classic definition of a woman born in the wrong body and the latter being more on a middle path? Does TS = woman, or does TS = TS? I'm not providing answers here, just saying there is a great deal of debate about this. Although ultimately I believe this varies according to the individual.