That isn't enough to disambiguate the meaning. In fact, your intended meaning is not even one of the options to disambiguate between.

Utilitarianism in practice means some kind of aggregation of all people's preferences. Most typically either 'total' or 'average'. Even though I am a consequentialist (at least in a highly abstract combatibilist sense) I dismiss utilitarianism as stupid, arbitrary and not worth priveleging as a moral hypothesis. Adding VNM to it effectively narrows it down to 'preference utilitarianism' which at least gets rid of the worst of the crazy ('hedonic utilitarianism' Gahh!). But I don't think that is what you are trying to refer to when you challenge VNM-X (because it wouldn't be compatible with the points you make).

How about "VNM-consequentialism"?

Perfect! Please do. 'Consequentialism' means what one would naively expect 'utilitarianism' to mean, if not for an unfortunate history of bad philosophy having defined the term already. The VNM qualifier then narrows consequentialism down to the typical case that we tend to mean around here (because you are right, technically consequentialism is more broad than just that based on VNM axioms.)