You should be able to tell if you will fit with another group of girls. If it seems like they are stretching to make conversation, or they keep telling you that they like your shoes, shirt, whatever, then you might want to think long and hard about that sorority. I really don't know what else to say, I felt a sudden "click" with my sorority, and I knew that that was where I belonged. You should never feel uncomfortable in a party and if your face hurts from a fake smile, then its probably not right. However, if you can relax and have a good time, then take that into consideration! Good luck!