Increase Book Sales/ Marketing Copy/ Niche messaging

I wrote a ebook about how to become a stronger and fitter hiker. I have sold 35 copies online in 2.5 months. I was planning to sell 200-300 per month or more. I created a website and run ads on FB/IG/Google. The cost of my ads is costing more than I anticipated compared to how many sales I was planning. I’m starting to wonder if it’s something that isn’t what people are looking for. Or my messaging isn’t clear enough. Or since it’s winter here in the US it’s the wrong season. I’ve thought about building a training guide to sell as an up sell. I’m looking for coaching to help me develop my business for hiking and my book, marketing and messaging. For example, I struggled with breathing and cardio on steep slopes. So I found cardio, exercises and breath work that helped me reach my goals.