Help! Is she interested or not?

I work out at this gym and this girl that works there started talking to me one weekend. I've flirted with her a couple times but nothing serious. One day she approached me after looking over several times. She asked me about my phone if I liked it or not. Then she wouldn't go away. She stayed and chatted with me for about an hour. She kept eye contact the whole time. And shared personal information. such *** shes been married, currently in a divorce, what music she likes, her sisters ual preference etc... I'm 17 years old but she mistakenly thought i was 20 years old. She is 23 years old. She is seeing an older man 29 years old. I asked her If she liked him or anything is serious she replied I don't know. This isn't the first time this happen I usually get attention from many older women in there 20's. It seems like I am the only one she flirts with at the gym. She's already made physical contact when I joke around she slaps my knee or something not very ual but what does that mean? Oh and I've asked for her number but she declined me on the spot, but then she said come see me after you work out. Note that she already knows how old I am at this point. I did not see her after I worked out. Was i not confident enough?