First of all, never make your sites and keywords public on an SEO forum!
Secondly - and since you already made your site public - I could take a look at it and, while I don't know Dutch, I could still see a few things that I would fix / do differently. Please note that these things may still not index your website, but if you change / fix / look into them they MIGHT index your pages. So...
1. First, are you using an SEO plugin? Because if you do, there is a possibility that your blog posts - for some weird reason - might be set as "noindex". And if they're set to "noindex" they will obviously never be indexed. Now, since you said that in your GSC things look fine I'm assuming that this is not the issue. But, it shouldn't be much trouble to check, just to be sure whether or not this is the issue. So, go ahead and check whether your SEO plugin, robots.txt or .htaccess files block the googlebot or tagged your blog posts with noindex. If you're using Wordpress also check whether other plugins - SEO or not - added the noindex tag to your blog posts. It shouldn't normally happen, but like I said, it's better to double-check and be safe than not check and be sorry
2. If everything at point #1 is OK, the next thing that could prevent your posts from being indexed is the quality of content. Yes, I know that everyone and their grandma are ranking with garbage (plagiarized, spun, machine-generated) content nowadays, but sometimes - for reasons that not even google knows quite often - your content might be deemed as poor quality content by google and simply refuse to index it. If this is the case, I don't know how to help you other than recommending you to brute force your way into google's index by building quality links to all those 9 pages.
And yeah, it might cost you an arm and a leg as quality links do cost a bit of coin, but... if you're desperate enough, you can try it. Or, you can try with lower quality links first, or by using some other (paid or free) indexers. But if your site has no backlinks yet (I was too lazy to check, but you should know whether or not your site has any backlinks) you should be cautious about using 100s of cheap-ass backlinks all of a sudden. It won't do you any good. So, it's best to take it slow by only building quality links first (start with some foundation links and get 80-90% of them to your homepage, and the rest of them to those 9 posts). It might not help, but foundation links are still safe, so it shouldn't sandbox your site either. And speaking of sandboxes...
3. Your site might simply be sandboxed. Sandbox is not a myth, despite of what SEO gurus might tell you, and some websites (especially in competitive niches) do get google's middle finger for up to 2 years even. I've had 2 sites created in September 2020 (in the education, and parenting niches respectively), and they didn't get any traffic (not even impressions) until August 2021 (so, for about 11 months). Now, I will be honest and say that I don't remember whether or not the websites have at least been indexed (they might have been, I honestly don't remember), but the point is that the sandbox is real and can happen for god-only-knows what reason.
In my case, the content couldn't have been the problem even though both sites have had thin and garbage content (only 10 articles of 400-500 words each, and those articles didn't even make sense many times, they've been written by "yes Sir, I give quality content if you buy from me, Sir" type of article "writers" on Fiverr). And the reason I'm saying that the content has not been the issue is because in August 2021 they have started getting impressions and lingering around pages 6-7 of google for some of the keywords in those articles. So, the same thin and garbage content, has not ranked anywhere for 11 months and then all of a sudden it's been deemed as quality content by google? Nah, it's just the sandbox effect, which your site might be in, as well. And if building links to your pages won't solve the indexing issue, then it definitely is some sort of sandbox if everything else I'm mentioning here is being checked / taken care of.
Also, speaking of thin and garbage content....
4. Many sites nowadays don't get indexed and one of the reasons is the thin and garbage content. While I have no idea how good your content is (I don't know Dutch so I can check it), I will still say that 9 posts might be too little. Try adding 20-30 more articles (and try making the content a bit longer, as well, especially if your direct competition has longer content than you), and then try indexing everything again, and see how it goes.
5. Onpage SEO... here there might be a few issues, because....
5a) your images don't have an ALT tag, and the ALT tag is an important part of onpage SEO. You might have the ALT tag, but I didn't see it. But this can easily be fixed, and to add an ALT tag to 9 posts should take you 5 minutes at most. So, go ahead and do it if you haven't done it already! I'm not sure how much of a difference the ALT tag will make in the indexing of your blog posts, but every little thing you do might help, so don't ignore it!
5b) you don't have the main keyword in the 1st paragraph of your articles. Add it! Also, read this guide to understand how to create content that google loves. It might just help with the indexing part, as well:
https://www.blackhatworld.com/seo/guide-full-example-of-how-to-do-on-page-seo.1251425/
5c) the affiliate links... I don't know whether or not this is true, but... in my undying, passionate hate towards google, I will still say it: google does not want YOU to make any money! Google is a greedy, ultra-rich and ultra-powerful company, and like most ultra-rich and ultra-powerful companies they want all of the money in the world only for themselves.
So, with this (unproven yet) but common sense principle in mind, it's easy to see why having affiliate links inside of your content is a bad idea. Google does not want you to make money, so if they detect affiliate links they'll simply not index the pages with affiliate links on them.
The solution? Either remove all affiliate links from your site until your content (inner) pages get indexed (preferably until they rank and get you traffic), or cloak them. I noticed that your website is on Wordpress, so you can easily cloak those affiliate links using the free Pretty Links plugin. Also, you don't need to have the same affiliate links so many times on the page, especially when the content is so short. It does look a bit spammy
And I think that's all. I mean, that's all that I've noticed at a first glance. If your domain is expired and has had some kind of penalty in the past then this might also prevent it from getting indexed. I just assumed that your domain is new and clean, but - again - if it's expired and it had penalties in the past.... well, I don't think any of the tips I've given you might help. So, you need to consider this, as well
So, in conclusion, check and / or fix the following:
- if the domain is expired check for potential penalties
- if it's new and clean domain, check if the noindex tag has been applied to your blog posts by an SEO plugin, or by other plugins you might be using. Also check the robots.txt and .htaccess files of your WP installation
- if it's sandbox, you can brute force your way out of it by building quality links (foundation links might work too, but only if it's not sandbox. If it is sandbox indeed and quality links won't help, then add more content... actually, add more content anyway because you have too little of it)
- if it's not any of the above (penalties, sandbox, noindex tags, thin content) then it's definitely the onpage SEO and / or affiliate links.
And if none of the above do the trick... I don't know what could be the reason. I would still just add more content in general, and build some links, but... your website is clearly visible on the forum and if google employees will see it they might deindex it altogether if you even mention that you want to build links to it. Better ask nicely a moderator to remove your link from your post
