When there's low search volume for your particular niche, it does make sense to see if you can attract traffic from peripheral niches and interests (which it sounds like you've been doing).

Sounds to me like your goal, from an SEO perspective, should be focused on long-tail traffic acquisition, though.

The way to focus on the right type of questions is to think solution focused.

e.g. what solution is your problem looking to solve.

Maybe you can look to answer questions like "how can I stop yo-yo dieting" etc. Any questions that your potential customers are likely to be asking.

Some good ways to find ideas for the types of questions people are asking:

1. Take a look at your Google Search Console queries, see what you're getting the most impressions for, double down on that type of content.

2. Reverse engineer popular websites related to your topic or closely related to your topic. You can do this using tools like semrush.com, searchmetrics.com, Spyfu.

3. Look at the types of questions being asked in forums related to your topic. Take those forum questions and start answering them in detailed blog posts.

4. Look at questions being asked on Quora.

Again, take the question and turn it into a blog post. Answer it in detail on your own site.

5. Collect feedback from your website visitors on the types of content they'd like to see you write next. You can survey them using tools like Google Surveys or HotJar.

6. In some industries, it might be that the offline content (e.g. industry magazines, medical journals) take off before the topics become popular online. If this is the case in your space, take everything you're seeing offline or in close circles and start writing about it more publicly.

Feel free to send me a message if you want me to take a look at the content you've been writing to start with.

Thanks,

Scott