99% of all websites I have visited are still not in GDPR compliance, although many of them claim to be..

May be I am in the 1% :)

I "believe" I am 100% compliant, but I keep reading, and "thinking" about every single detail, in case I missed something or in case I can do again better.

But since I rely on third parties for ads (yes, I know it's bad), my incomes from EU visitors was divided by two. Hopefully, this is only a tiny fraction of my whole incomes, so I am fine with this. I am not blocking or bothering EU visitors.

Good to know read of your concern..
But..If by

not bothering EU visitors.

you mean you are not showing them a GDPR notice ( with the option to "continue" using your site without cookies or tracking, including tracking by ad networks ) ..and you are using an "ad network" who tracks ( even via IP addresses )..Or , if you are showing a GDPR notice, but in order to even see it the EU visitor must "accept scripts", and this means the tracking ( by either your site or your advertisers has already happened by the time they see the notice)..then..
The bad news is ..if any those scenarii apply to your site ?..you are not GDPR compliant..

I meant :

- I show a non invasive banner, at the bottom of the screen, asking if they accept, or not that third party ads be displayed, and I do mention, right at this banner, that these third parties may track their activity online, (and with a link with a page with more details),

- If they make no choice, I continue to show the banner at the bottom, but don't show ads,

- If they accept, then I reload the page, and will show third party ads, and I leave a tiny link, in case they want to change their mind. To remember their choice, I write a cookie, which expires as soon as the browser is closed.

- If they explicitly refuse, I reload the page, still without ads, and without this banner,

By not showing ads, I mean, no third-party ads, something, it happens, I show self promotional creatives :)

- I don't log visits, I only count page hits, the time of the hit, no IP, no referrer, no UA,

- I don't rely on third parties, excepting for ads,

I didn't understand what you meant by "EU visitor must accept scripts".

Do you think I miss something important?

EU visitor must accept scripts".

A lot of sites show their "banner" or "message" only to visitors who allow scripts, so if like me , the visitor blocks all scripts , then the EU visitor will not see the banner..That is not a problem, because there will be no 3rd party tracking of that visitor..
But..if in order to see the banner, the visitor has to allow the site to run "scripts", then 99 times out of a hundred, the visitor allowing scripts on the site, will be simultaneously allowing tracking by Google analytics ( which so many sites use )..A huge number of websites will not work ( visitor sees nothing, or major functionality of the site , such as navigation etc will not work ) without their scripts ( Google analytics, calls to Google apis, Google ajax, Google fonts etc ) all of which track the IP of the person on each page, and on each page reload in the case of calls to ajax.googleapis.com..This site WebmasterWorld works like that..

You sound like you are fine..depending upon how you serve that banner, if it requires that the EU visitor allows "scripts" from your site, and if your site is running Google analytics, then you are not "fine"..Because Google will know they were on your page, even if they subsequently "decline" ..If they came from Google SERPs , then Google already knew their IP and their search , but if they came from elsewhere...

OK.

I don't use any third parties, excepting for ads. So no Google analytics, no social networks buttons, etc... Also I host everything myself, I don't even use CDN, all (excepting ads) are served from my server.

Cool :))

The DIY method is the best! Few work that way, taking the cut and paste ease of use. Do it in house and you are fine. All you have to do it take of the logging functions which are part of the GDPR....

I wonder how companies like Criteo are doing. Their business model is based entirely on tracking.