The Galaxy Overlay is currently disabled for the game. Hence, no Achievements.

So I wont receive any because the overlay was automatically disabled?

I believe so. I heard that disabling the Overlay was a last-minute change by CDPR because it was causing crashes. Presumably, it will be patched soon. But without the GOG Galaxy in-game features (Overlay) active, pretty sure Achievements will not function.

I played around 2hours earlier today and got one achievement to unlock. Maybe there is a problem that was common to Witcher 3 - Galaxy registers and shows all achievements, but some with a few hours of delay. Backend probably gets some serious use right now.
Edit: But judging by the prevalence (or maybe rarity? ) of "my" achievement and what it's for it doesn't seem to work for most of the players.

Yesterday I got an achievement for 2 headshots with one sniper bullet, but I did not get a story related achievement. I really hope that these will be fixed (and retroactively!).

After the patch, I decided to restart my entire game and achievements went through

I've gotten a total of 1.
Given that every exit of the game for me after the first launch has been a crash, that doesn't surprise me.

Galaxy updates the achivements after exit... if the exit stuff never happened....

43 hours my dude and what i got?...

So the solution is to restart the game and you'll just automatically unlock the achievements you should've gotten otherwise on your other saves?