New to PUA -- looks like one hell of a site

-- and I certainly could use some advice on a situation involving a girl I met sometime ago that am still pursuing. Let me explain:
Many, many months ago I met a girl at a local event I go to weekly on Wednesdays. I had interest and decided to introduce myself eventually and it seemed liked we really hit it off and talked for a lot of the night. Once the event ended I headed home and added her on FB which she accepted immediately, and we ended up actually talking for a couple hours more. Finally it was time to go to sleep and she signed off. At the time I was still a bit timid and shy and decided to send her a message the next day asking if she wanted to grab coffee, and long story short she never gave me a really clear cut answer to which I assumed it was a no. I didn't talk to her much after all that happened.
During the next several months after all of this I had started getting into lifting and mma and pretty much had no contact with her at all... until a couple weeks ago.
I ended up seeing her at this other event one night and when she saw me I was a little surprised by her behavior. She seemed excited to see me in a flirty way and was making comments like "why are you standing over there? come over here and talk to me

" This event was a presentation sort of deal so I eventually had to take a seat with her sitting next to me and we started catching up. After it was all over, I offered to give her a ride to a bar everybody was meeting at, as well as a ride home which she took. We had great conversation the whole way there, at the bar, and back -- all the while I was receiving good signs like her breaking the touch barrier and so forth. The morning after she messaged me on FB telling me she had a great time and it was great to see me.
So right now I'm thinking I am in good shape, I should pursue right? Well I am unsure... The deal with this girl is she seems really busy all the time, and when I send her messages and what not just being friendly, I get no reply! The following week I see her at this bar again for my weekly event -- which she starts showing up to -- and again we hit it off. Somehow I ended up giving her a piggy back ride and running through the bar with her in a race, I was a bit buzzed. And just in general things were fun and going well. But all the while I can't tell if she is doing all this in a "friend" way, or if it's because she is showing interest. Her personality is a bit nerdy, but at the same time she has a very clear mature side as well.
So far I have basically kept it cool and honestly have not messaged her at all. I'll probably start seeing her every Wed. again but do not know how to salvage the situation and take it to the next level if that is even possible at this point. I think my issue is that I cannot read this girl at all! It's hard to explain but in person at the event we're fun together, but outside of that there is nothing and we do not really talk! Help me out PUA!