I was at work the other day and I complained that "my room gets too hot." I was immediately rebuked for calling the "office" a "room." Honestly though, what is the difference?
ETA: I've always considered an office to be the collection of rooms associated with a business. and as an extension, I have always called the building containing that collection of rooms to be an "office building."
Best Answer
An office is a kind of room (technically 'office' is a hyponym of 'room'). There are presumably lots of other rooms in your building that are not offices: a kitchen, bathrooms, common areas. And you are probably the only user of that room.
So technically you were correct. It is a room and it is yours alone.
By saying 'room' it sounds like you might have been referring to some other kind of room than an office (though of course an office is pretty much your own so there shouldn't be a misunderstanding. But 'my office' sounds more natural. To say 'my room' for that place is technically correct, but pragmatics leads us to expect that you should call it specifically what it is rather than the generic. Sometimes using a generic sounds like you're pointing out that it is not specifiable (a generic room with no particular characteristics to set it apart from others), which it is.
Also, because words aren't understood always logically but in their most commonly used contexts, 'my room' is more likely to be used as a reference to 'my bedroom' (where one sleeps at night). And that is very distinct (usually) from a room where one works with a desk (that is not a bedroom). That's not to say that 'room' evokes a room with a bed but that it may have that slightest of unconscious inklings that it is not very office-like.
I'm surprised that the subtlety led to your being rebuked ('rebuke' seems a little harsh). I can see someone saying "Your room? Did you mean your office?" which is not a rebuke but a clarification.