I say this as a girlfriend you're not and you shouldn't let anyone tell you otherwise, and make sure you think through about what you say if you do
But I agree with everyone else that this is a girlfriend that sounds horrible in the long run. You guys are young, you don't have to feel stuck to her. But what she did shows she doesn't care about your feeling AND that she could keep hurting you in the future. She didn't even ask you how you felt about it later. Sure that cuddle felt good but being with someone who makes you feel jealous or insecure is terrible bc you'll never know when they'll stop.
The fact that she thought it was okay to put her head in someone else's lap shows that you guys have different levels of acceptable in your relationship, especially HER with the blowjob. Sure it could be okay for some girls to put their head in someone's lap bc it really is just innocent for both the girl and the lap person but for THEM it obviously was not so gf is not the type who could innocently be affectionate with others
If people say you're whiny or controlling say they're ignoring your feelings that normal people would have and not be okay with their behavior. Put your foot down and say you won't tolerate it or else you'll see her doing more blowjobs or worse, infront of you or behind your back.
Imagine her with a dude and she thinks oh you were okay with her giving a blowjob infront of you so you should be okay with it in general. And what's worse is if you don't at least make it clear that you're not okay with it, she can use it to justify that she didn't know you weren't okay with it if she cheats on you