What do i do next with this girl?

You can't take what happened last night as a gauge for her mind on you simply because you met her at the party, meaning that you didn't go with her. She could have come to that party under a different plan. You knew her since about 2 wks, but apparently failed to indicate you have interest in her. So what to do now is declare your interest in her as soon as possible - approach her as appropriate. Then do the normal chasing. She will consider you, if she's still available.