Yes

You went to change first, no chance you would attend in your quidditch fangirl uniform. You don't really have classy-party clothes, as you tend to hide your body. Your mother taught you well... But you don't want to look to childish this time, so you hope your outfit will allow you to blend in. You choose a tight top and a tennis skirt, at first you are satisfied. But a longer look in the mirror makes your realise that your outfit emphasize your feminine silhouette, more than you are confortable with. So you toss a jacket on top, and go, you are already late.

You all meet in one of the boys room, and it feels crowded. Yes it's a more private party, but it's still 7 players and their close friends. When you enter the room, everyone look at you, you even hear a wistling sound. Clearly, showing up without your regular outfit is surprising.

At first you are well behaving, or shy. But as the time pass you relax, and chat casually, you know this people for a long time and they seems genuinely happy to see you open up. Even your roomates are there, and they never saw you having real fun.

Then, they start to pass around some drinks, smuggled. You try to refused at first, but you yield to the peer pressure. It takes only a few drinks to change your behavior as your not used to it. No one in the room have seen you like that, you are more talkative and funnier. The girls genuinely enjoy seeing this side of you, for the first time you understand that you missed a big part of student life. The boys also discover a new you, unitentionnaly showing up her body, your jacket tossed aside.

Emma saw the look you are getting, and she wants to protect you. In your state you are an easy target, in the best case you will ridicule yourself, on the worst one you will follow the wrong guy. That's why she decided to send you home.