Well, you were violated that much is for sure. You did not give her consent to touch you under your pants, nor did you give her consent to kiss your neck ETC. I mean, unfortunately its been six months and the chances of them finding any evidence or anything will be slim to none. You could absolutely report it to the police, but it will likely be a he said she said type issue as this other woman will probably insist that you were all over her as well and it was consensual. But yes you were absolutely assaulted.
Im going to be 100% honest and blunt with you. This was a very close call for you, thank god you were not gang raped by her and a bunch of horny drunk guys. What happened to you was wrong, but it could have been SO much worse. Your young, you live and you learn. You have to really protect yourself when your at these parties. If you drink, do not get super drunk. Always have an escape plan, never drink anything that someone gives you, you get your own drinks. I would tell you not to drink because your underage, but I know that's not going to happen so I am giving you solid advice. As far as them victim shaming you, they can go sh!t in a hat. You got taken advantage of by an older female when you were impaired. That's not your fault. Like I said, let this teach you to be vigilant at these types of get togethers. Be careful out there. This is a sick world.