Should I make a move?

[Jeremy]

Alright so since I met this girl I'd been texting and I even went to her church. Well at a recent college fair (highschool senior) I didn't go up to her every time I saw her cause I didn't know her group friends but a few times I sat with her. Well Saturday that week she hung out with this boy (at one point he had his arm around for a short time) the whole day and I felt hurt. I figured I was out and started to focus on other things well when I got home that night I saw she accepted my Facebook request a few minutes after getting in and I know that doesn't mean a whole lot but I thought ehh she doesn't hate me. And the next day I texted her apologizing for me not always talking to her and she said don't worry about and that she didn't see it as me ignoring her and I've been talking to her throughout the week and she invited me to some event on Halloween night. I'm confused sometimes I feel I missed my chance but sometimes I feel like if she's still talking to me maybe I have a chance. I feel like I should say something at this event but I don't want to ruin things for good. Should I tell her how I feel at this Halloween event or just ask for a date or back out? We use a alot of smiley faces when we text idk if that means anything I just thought I'd add that.