One of the options is this questions is "very". Since in most cases in english this is functionally equivalent to "so" that should be accepted as long as that is an option.
No, it is not equivalent.
How are "You weren't supposed to" and "you shouldn't have" the same thing?
They aren't. Who told you they are?
Well, both are possible translations of "Neměli jste..." I guess context decides.