Friendly or flirty?

Well I haven't been on here in a while and I haven't dated in quite some time so let's just say that I'm a little rusty. Don't want to make this too lengthy but would rather give more details than less, also going to try to avoid specific details for anonymity reasons. Anyways I met this girl through my sister. She's more an acquaintance than a friend of hers. Normally she's not the type of girl I'd be attracted to but her personality really had me going. We met at a bar celebrating my sister graduating. We talked on and off the night, I jumped around a bit from people to people...didn't want to come of as too aggressive, but did flirt a little bit.

Anyways that same night when we get home she added me on facebook and left a post on my wall...we had been joking about something she could do for my sister that I really wanted as well and she told me she'd do it for her but not me jokingly with a smiley. I responded saying she was mean blah blah blah, jokingly of course. About an hour later she sends me a decent length private message saying that joking aside she'd do it for me and my sister. She also invited me and my sister to an event this weekend but unfortunately we couldn't go. Then at the very end she leaves her phone number...which I thought was a little odd considering she could have always contacted my sister or kept contact through facebook.

So I figured I'd just text her a response, basically told her thanks for offering to do it but I was just giving her a hard time. As for the weekend unfortunately we can't attend we have something going on but maybe some other time we could do something. She responds saying have fun and some other stuff. Then sends another text about something we were joking about when we met, which was kind of mean (jokingly of course)...I tell her she's mean. We go back and forward with small chit chat texts, telling me about where she was at the moment asking me if me and my sister had been...then I sort of just stopped texting because really don't know how to end a texting and it was late.

Two days later she sends me another text out of the blue telling me what she just did which is something that she knew I would love to do pretty much to rub it in my face. I just respond with a short message, saying sounds fun with a frowny face. No response back.

Then the next day she sends another message asking if my sister was with me where I told her we were going and I said yep.Told her what we were doing and what was going on...few jokes back and forward for about an hour, then conversation just sort of ends again.Which is why I hate texting...

So yesterday which is two days later I decided to mess with her this time and send her a really nice picture as a sort of "don't you wish you were here." We started texting for a while about what we were doing, she was basically in the middle of nowhere for some event she was doing and jealous of where I was. She was telling me her plans, and sort of went into about herself and something about herself that she doesn't like because she didn't grow up with people like her, I pretty much told her the opposite that I grew up with people like you and I like them...we had a few more jokes and she invited me to some other event later next month. I told her I'd have to think about it, cause it's pricey and sort of crazy/dangerous. haha

My sister isn't really much help...I showed her the first message on facebook initially but not the following ones and haven't even bothered telling her we talk. She said she's super friendly and probably just being friendly...but iono this seems a little too forward to me, especially since she's talking to me instead of my sister. I'd like to hangout with her again and maybe if I'm feeling good vibes just flat out ask her out there, but at the same time I don't want to drag this out long and get friend zoned. I think the first event she invited me to would have been perfect but I couldn't attend unfortunately. I hate texting and would never ask someone out through a text, but would find it sort of odd if I called her out of the blue and asked her out. I was thinking of inviting her out with my sister and maybe some friends to maybe go bar hopping or something. But unfortunately due to time and planning that is quite difficult as well. Anyways I'm at a loss. If more specific messages or details of conversations would help I could PM people, but would rather not post them directly on here.

I've always been quite good at reading girls that like me but with this one I'm having a tough time.