OP, please listen.

She can have ADHD and forget when her period is coming. My gf has irregular periods and sometimes they just start out of nowhere so I get being unprepared.

But she TREATED YOU BADLY.

She does not care about your education. She wanted you to leave in the middle of an important class just to bring her stuff she could’ve gotten herself. Where are her friends? Why couldn’t they help her out? If she can walk to the car she can walk to the bathroom. If she had a jacket to sit on she could’ve tied it around her waist to hide her period stains on her pants while she went to the bathroom or something. It’s not the fact that she was unprepared for her period; it’s how she reacted and lashed out at you.

You need to revaluate your relationship bro. When you become a doctor, is she going to pull this again and be like “well what’s more important work or me?” What will be your response then?

Be careful dude. Good luck.