You seem to be conflating utilitarianism with a specific variant of utilitarianism, perhaps hedonic utilitarianism or perhaps preference utilitarianism. Utilitarianism simply says that the good is whatever maximizes aggregate welfare. Welfare is a free variable here and can be, on the basis of the beliefs of the utilitarian, among other things: desire satisfaction, hedonia or eudaimonia.
You seem to be conflating utilitarianism with a specific variant of utilitarianism, perhaps hedonic utilitarianism or perhaps preference utilitarianism. Utilitarianism simply says that the good is whatever maximizes aggregate welfare. Welfare is a free variable here and can be, on the basis of the beliefs of the utilitarian, among other things: desire satisfaction, hedonia or eudaimonia.