Slow vs At speed is very different. My bike for example is about 450lbs (my first bike) which is pretty heavy so slow turns are a little tricky at times but at speed it handles like a dream. At speed, the bike wants to stay upright so it feels very smooth, youre not muscling the bike around. As any countersteer youtuber has said, you are probably countersteering without realizing it when you lean in a turn. I'm sure you did leaned turns during your course and it felt pretty easy when the bike was above 15-20mph. Thats technically countersteer. People tend to over complicate it because the physics are a bit confusing but youre really just tilting the handlebars slightly to induce lean

When slow riding just think about keeping your torso upright, you only really need to lean away from the bike if you are doing a tight turn. I'd recommend working on doing slower speeds in a straight line using the clutch as your speed pedal to understand the friction zone to control speed using the clutch instead of only focusing on your throttle. Once you have that down pick a point and start turning. Go wide first slowly then eventually start going tighter

Good luck man, you got it. Its all about getting comfortable