Fatinah. Thanks for posting this thread!
The same thing happens to me too, and it is a relief to see that I am not the only one “afflicted”!
Personally, I believe it has to do more with psychological reasons rather than physical. I dance better when I am concentrated in the music and aware of my body movements. Stress or preoccupying thoughts interfere with this, and I end up making a mess out of my practice.