How is your Finnish?
I'm happy to see people here on HN respect the difficulty of learning languages. Most foreigners that speak Finnish do it very poorly at first and even after decades they still sound like foreigners. But it shows huge respect to our small country for someone to make the effort, and we really appreciate it. I'm hoping other people see learning their own mother tongue the same way. Sure, most of us need English, but learning it well is still a huge task.
I spent my preschool years in a multicultural environment and English was our lingua franca(ironically the school-mandated language was French), so I didn't properly learn contractions until grade school - same with similarly sounding words like "than vs then" and "your vs you're".
It's because they have two different uses (three if you count nested quotes, but those aren't common and are pretty easy to figure out), contractions and possession, and they seemingly collide on words like "its" where you'd think it could mean either.
Not sure if you've already learned this (or if it helps), but English used to be declined, and its pronouns still are, e.g. they/their/them. That's why "its" isn't contracted; the possessive marker is already in the word.