Hai bund! Don't worry lah, nurse KK tu probably just being extra cautious, which is actually good thing. A few of us mums started counting kicks before 28 weeks also, the idea is just to get familiar with your baby's normal pattern, so you know what's "normal" for YOUR baby, not a strict rule that must start exactly at 28 weeks.
The movements do change in third trimester, they become less fluttery kicks and more like rolls and jabs, so some mums think baby is moving less when actually baby just dah besar and space is tight! But if you notice an hour pass with zero movement, it's always better to go to PAC and get checked out, just for peace of mind, they won't marah you, I promise. Doctors prefer you to come in than worry at home. Since everything looked good at the scan, that's already very reassuring. Just do the kick count when you've had a rest and a snack (baby moves more then), and trust your gut, if something feels off, go get it checked. All the best!
Fadilla Zaki