Is it possible for my legs tremble but no one can see it?

[SVH_2020]

That sounded kind of weird so let me explain for a bit.
I used to have a lot of problems with standing and presenting in front of class, since I was little I used to hate being in the front, would always look at the back of it, or the floor or anything except for my classmates
The same is for singing, I like singing a lot, so I used to go to classes before online school and such, I did use to have stage fright until I got to sing in front of a crowd for the first time, I still get nervous but not as much anymore
But back to the point
When I'm being the center with either singing or just presenting in front class, I reaalize that I start to feel like my legs start to shake and tremble, like I could collapse any moment but at the same time I know I won't, sometimes my hands would shake as well, but that is kind of rare and only happens in singing while holding the mic
But the strange part is when my friends tell me I do well, I told them if they didn't saw me trembling, and they say they didn't...
Like I don't know how I still could stand, but they didn't saw anything?
Am I imagining things? or is something else? I always had that doubt

 

[Cuchculan]

It is possible. Have had it before. My legs just felt like I was about to fall to the ground. But nobody else paid it any attention at all. Guess they did not notice. So it was simply me feeling it. Not clear to them to see. So it is possible.

 

[8888]

I agree with @Cuchculan that it is possible. They could be moving but it is so little that it's hard to visibly see.