...the culture where being stressed out of your mind is a virtue.
It's wild to me that this is so universal across national borders. A friend of mine did IB in Mumbai, I did it in Nebraska, and you did it in Sweden, and we all complain about the stress culture. I promise that my first year of college was much easier than IB, and by the time it ramped up I was prepared for it
And it's okay to be scared! Just try to focus on your own growth and well-being, I have no doubts you're going to kill it :)