9 months building my app — finally got paying customers, but sales are inconsistent. What am I missing?

I’ve been building a consumer app called KinScan for almost 9 months. Recently I got my first paying customer , followed by a few more purchases. But sales are very inconsistent — one purchase, then nothing for days, then another one. I’m a developer, not a marketer, and honestly feel a bit lost about what to fix first. For those who have experience with consumer apps: How would you diagnose whether the problem is traffic, positioning, conversion, pricing, or the product itself ? What metrics would you look at first? What marketing channel would you test with a small budget? I’m not looking for generic “do social media” advice. I’d really like to understand what might actually be broken and what I should test next . Any advice from people who’ve been through this would be greatly appreciated 🙏