Welcome Terje
Check out the sticky at the top of the forum to see how to film your squat next time. I'd be able to tell you more from the appropriate angle.
Are you doing tempo squats on purpose and deliberately lowering yourself so slowly?
You're trying to keep the torso too upright as you descend. That's why you feel like you can't keep your balance unless you go so slow. The problem is, you're learning to squat on your heels.
Get your eyes down about 1-2 meters on the floor in front of you, then lean over and send your ass back away from your feet as you descend. You'll be surprised at how you're able to better balance.
Work on that for now. And make sure you're hitting depth each time. A couple of these reps were close.
Good luck.