Thanks for your replies, I appreciate it!
I am playing as the default one, no changes there.
Man I wish. As I wrote I can maybe find 3 to 4 berry bushes and each of them will just fill that hunger bar by maybe 10%, so that is way too low to survive. Maybe it is what @MKMoose is saying and I don't spot them, but I make sure to move the cursor over the objects and check the respective names of the plants.
When I travel to find mushrooms I "spent" so much of the hunger bar that when I finally find a few, I am in a worse position than before.
I already did that, but those berries take 7 days to respawn; that is way too long to survive on them.
But for a cookpot you need clay (it seems) and I have not yet found any clay in any of the maps. That stuff seems to be harder to find than ores (which I have seen plenty of already, but of course I don't have the tools to use them.
But cattails are even harder to come by. I can barely find the 10 required to progress in the tutorial.
Again, thanks for all your help. Maybe I will give it another try on the weekend.