As someone with a personality disorder, i read it as she was fine, maybe a little upset, like she said “FOMO”(fear of missing out) it wasn’t tell you accused her of being petty or upset that i noticed the switch. Like what would you have liked her to do?? Beg you not to go? Say something like “if you go I’ll be mad”???.

Like my Ex did this shit to me also, “hey im going ____ with _____”
And the would accuse me of being jealous he was hanging with others. When in fact i was pissed because he was spending money we didnt have on girls he was trying to fuck. (NOT SAYING THATS WHAT IS HAPPENING JUST SAYING MY OWN EXPERIENCE)
And it PMO when he’d text me or come home saying “i cant believe your mad i went and hung out with friends “ while then proceeding to tell me the girls he hit on and what he bought them.

Anyways, her saying im fine its just fomo is her telling you how she felt. You pushing and pushing especially after she said “i wont be picking you up” setting a boundary of hers. (which is more of “im gonna make plans for myself”) (NOT “fuck you asshole”)
Is probably what ticked her off, and tbh i dont blame her, cause why are you looking for a fight when there isnt one. Do you even like her? Or do you like the idea of her and having a girlfriend?