Is there a coherent conception of value that does not function additively?

I want to maintain the notion that ordinary human life as lived is valuable. I want to therefore avoid nihilism.

I want to avoid the notion that a simple calculation of pleasure over pain can justify life. That is because I want to avoid a number of conclusions: that large portions sof my life were on the whole more bad than good; that (relatedly) I do not have the authority to retrospectively declare a painful period valuable, even where the lessons it taught are unlikely to generate enough pleasure in the time remaining to outweigh the pain of that time; that most people who have ever lived constitute an active detriment to the amount of value in the world; that we have a responsibility to create as many minimally satisfied persons as we can.

I am also skeptical of our ability to measure pleasure and pain coherently enough to determine of any moment or extended duration whether the net impact is more pleasant or painful. I reject the notion that we can determine this with reference to whether someone would choose to live it again, since such choices may well be made with respect to an ethical theory, which pre judges the question.

It's all very well to do what God commands, to develop virtue or to follow the rules that any rational self respecting person who acts according to reasons might do. But to me these theories seem instrumental. And the value of the thing valued (acting with respect to the will of god, human flourishing, rational consistency) can be additive in the way that gives rise to the repugnant conclusions.

I am skeptical of the intrinsic and instrumental value distinction. I think it's no coincidence that this notion of value seems to arise around the same time that economics appears, flattening all values into revealed preferences with an implied monetary value.

Is it possible to rescue a theory of value that avoids these problems?