Embarrassed to ask this but…

How do I know if i orgasmed?? I have received oral sex before and each time my legs were shaking

TMI I always thought that was coz of the position i always did with him for oral sex- I would lie on my back and he would have my legs lifted up all the way to my head, i would basically be in a folded position.

Could it be because of that? Or is that my orgasm?