That doesn't surprise me. At all. Psychiatrists are trained to diagnose (and tools like the DSM and psychological testing) largely in terms of deviation from the norm. This isn't necessarily a bad thing, as the evidence suggests the majority of patients can often see significant improvements in quality of life through treatment and therapy, but it does predispose practicioners to believe that deviation itself represents disorder. That approach makes some significant errors in understanding statistics (no one says that the mean of a set of numbers is the "correct" number, for instance), but for most of the patients seen by psychiatrists, it doesn't negatively affect them. A more reasonable approach might be to ask whether that deviation is negatively impacting a patient's quality of life, such as you'll often get with depression.

That would acknowledge the normal diversity of human moods, behavior, and minds while viewing psychiatric treatment as a means of empowering patients to improve their lives rather than just a means of "fixing" what a practicioner perceives to be broken. A lot of people, far more than those who actually seek treatment, could benefit from psychiatric tools, therapies, and treatments. That's not the same as saying they're broken or that they should be medicated.

Anyhow, your experience would be a good example of how the normal approach can fail. With set theory, psychologists refer to something called a "perceptual set," which is just a series of predispositions that shape how we perceive external stimuli. Psychiatrists look back to past cases when they're diagnosing new patients, and they all draw parallels to them the same as others draw on past experience. It's a huge part of how we learn.

Unfortunately for you, that means they're thinking of cases where the patient was anxious about various conspiracy theories. You managed to get lumped into that category because she's heard it before, and lacks the specific education to understand the difference between concerns about encryption/internet surveillance and conspiracy theories about NASA and the moon landing. Congratulations, you've been stereotyped and likely mis-diagnosed as having some (minor? major?) paranoid tendencies. If the root causes of your anxiety are misunderstood, it becomes more likely that th misunderstanding will negatively affect how it's treated.

That's actually a huge part of the problem with the political fight over encryption. People don't understand it, so they fall back on analogies and ideas that they do understand and attempt to apply them to this new, unknown stimuli. It's a powerful method of learning, but when it fails, it can do so spectacularly. People see encryption like a lock on a safe or a sealed letter, not realizing the differences or the universality and negative consequences of things like backdoors.

That said, don't give up on psychiatric help and therapy because of this one experience. Finding a psychatrist you connect well with isn't easy, and they understand perfectly well that there might be better options for their patients out there. It's possible that this experience has undermined your ability to work well together in the future. You never should have walked out of the room feeling like she's labeled you as "nuts" and that that was the end of it. In that respect, she failed you. Maybe it was word choice, or maybe she didn't explain certain things to you. Whatever the case, you might be better off seeing someone else.