Exploratory user research: how to do it and exploit it efficiently?

Really need your advice and thoughts here.

I'm working on user / market research for a mobile self-help app which helps users self-diagnose their mental wellness and seek external help if they need.

The organization of the project is peculiar in a way, in that the app has already been developed and distributed without any "preliminary" user research. The PMs wanted a product really fast, so they they started out with assumptions of what users would need and developed from there. (Note however that we DID do several user tests as design & development advanced, however these tests were more focused on usability and less on product desirability or relevance to user needs.)

At this point PMs want to add a big new feature. So my team (who all have design background, not research) and I decided it was a good time to do a long-delayed user research on how people deal with their own mental health perception and seek for help.

We interviewed a dozen random people. We didn't show them the product because we weren't focusing on product usability or desirability. Rather we wanted to discuss their goals, strategies and obstacles on dealing with their mental health (Interviews aren't probably the best method owing to people's selective memory & bias but it was the cheapest and most accessible way).

Interviews were really interesting, I have tons of info. But my challenge is that a lot of this info is by nature very unstructured and it's quite challenging to put it into a structured form. It definitely has to be structured in order to make sense out of it (otherwise we'll have a hard time using it for development) but I'm resisting pressures from my team to structure everything in a persona + user journey form. "User journeys" the way the team expects are very clean, chronologically consistent. Whereas what I found out is pretty chaotic and with a lot of individual differences. I can make up a sort of formal system, just it's not in the formalism they expect. For me it's becoming "voodoo science" to try to force results into a special format, whereas I want to be honest in my approach (i.e user research is useful to have a contextual picture of people's complexities so we can service them better, but that doesn't mean that we can extrapolate and build user journeys that reflect every situation. Rather I want to describe the different "processes" in which people evolve, in a free-form I have yet to work out.)

For the record I've been working in UX research for the past 7 years, but mainly doing user tests for validating and improving apps. It's the first time I've done high-level exploratory research for product definition. I'm wondering at this point if this research was a waste of time, and if we should have stuck to designing something (anything) from our initial assumptions, test it and start from there.

Sorry if this post feels messy and vague, that's because probably I have to explain better what my team expects by "user journeys" :)

Thanks a lot for reading,