if you have no money to invest I don't think you'll rank in google. Just saying
Try to get traffic by participating in forums, on social media, do some Pinterest / Quora, etc...
Also, in order to rank in Google for that niche you might need a Disclaimer page in which you tell your visitors that you are NOT an accredited Reiki practitioner (or a medical practitioner in general) and that they shouldn't fully believe in everything that you say. Maybe what you say it's true and you mean well, but google likes to see that page for medical-oriented sites, so add it!
And just because you add the Disclaimer page doesn't mean you're going to miraculously rank and bank tomorrow, so don't expect this! But the page still needs to be added
And if you ARE an accredited Reiki practitioner (in which case you might not need the Disclaimer page) you should add an About Me page and brag on that page about all of your skills, experience, diplomas, etc... all of that crap that google loves to see for people giving health advice. EEAT is real when you're a small, random nobody so make good use of it or else I don't think you can ever rank in google with no money, no expertise, no experience, no trust, etc. Lately (and probably from now on) Google will only be reserved to the rich, the businesses, and the hackers, so if you don't fall in one of these categories it will be hard to see success with SEO...
Also, I would hide / unpublish the Amazon store for now. First, focus on getting a constant supply of traffic (say, a few dozen visitors a week for starters, but make sure that you get them week in and week out, otherwise I don't think it will matter if you buy a traffic gig from somewhere for 1 week or 1 month and then stop), and once you have the traffic you can monetize it however you want (including linking to Amazon since this seems to be your choice). But if you have no traffic yet that Amazon store won't do you any good, especially since google hates affiliate sites and your site - having no traffic and no rankings but being chock-full of affiliate links already - will definitely not look good in google's eyes, which will make your mission of ranking in google even harder...
Last but not least, you should probably make a Contact Us page and move your email address and a contact form on that page. I don't know if that page helps or not, but since most sites have it I assume that google expects to see that page on your site too, otherwise they might consider you a random nobody (which you are, and which google doesn't like anyway despite of what they say), so make sure to add the Contact Us page, it will only take you a few minutes...
Overall, your site looks pretty weak (no authority, no EEAT), so I find it hard to believe that you'll rank in google with such a weak site, which is why I recommend you implement the few small things that I mentioned earlier, and also try to get traffic in other ways if you can while - at the same time - getting some quality backlinks to build up your site's authority. With decent constant traffic and some decent authority (and those 3 pages that I've mentioned added to your site) you might get a bit of trust to impress google to rank you for some long tail keywords which - by the way - should be your main focus since it might be hard to rank for keywords with high traffic and high profitability with a low authority / trust site in this niche...
One more thing... I don't understand the siloing of your site. More specifically, your categories all seem to have the absolute exact same posts, so what's the point of having different categories then?? Maybe there's a point, but I'm not seeing it...
