I need advice plz :/?

I met This girl at my sisters bday this girl is 22 and I'm 20. We flirted the whole entire night and kissed and everything. I texted her and asked her to dinner sometime she said yes with a :). Later that day my sis told me that girl has a bf. But she's still been flirting and texting me and said I should come over sometime. The next day I made a dinner date and she said def if she is not working. Does she like me is that why she hasn't told me about the bf? She hasn't even mentioned having one at all. Do I just go along like I don't know? I know we just met but I really like her