A good place to start might be a book like 'Autocracy, Inc.' by Anne Applebaum. Unrelated to this but her book on the Holodomor, 'Red Famine,' is amazing too. She's an expert on modern authoritarianism. The book's about autocrats in general but deals a lot with disinformation and propaganda. It'll give you a pretty high level view of who those people are, what their goals are, and how disinformation fits into their strategies. A big part of recognizing disinfo is being able to evaluate whose interests a piece of (dis)info might serve.
You'll find a lot of books about Russian disinformation because Russia has been the most active, the most ambitious, and the most successful at weaponizing propaganda. I'd look for books written by academics but who are writing for a popular audience. 'Active Measures' by Thomas Rid is an example. That book in particular goes into the origin of disinformation in the Soviet Union (the term was actually coined by Stalin) and how it carried over into modern Russia. Russia's a good starting point too because everyone else has copied them like crazy -- although they're now openly collaborating, Republicans are stealing from this playbook.
Bellingcat is good resource to get into the anatomy of disinformation networks and operations. They're the gold standard in open source investigations and have uncovered some insane shit -- disinfo networks, Russia downing MH17, a network of Russian illegals (like in 'The Americans'). Reports like this one are extremely detailed and get into the nuts and bolts of how propaganda networks are structured and how information passes through them. Their ability to track down spies using the Russian equivalent of door dash is internet MacGyver shit too.
Caroline Orr Bueno is a disinformation researcher whose newsletter Weaponized Spaces also dives pretty deep into disinformation networks, often tracing it back to a single point of origin. She links to a lot of great resources and is super accessible. She's also awesome. I assume she's moved on to bsky but she used to be on Mastodon and would answer any questions you had about her work. Good person!
Do your parents need to know why you need to go to the doctor? Can't you say it's for some other, less embarrassing reason? Not that you need to feel embarrassed but I don't think your parents will be harmed by the white lie. And it doesn't really change the outcome for you, right?