What signal is this girl giving me? Red light and turn around? Yellow light? Or green light and go for it?

This girl Lexi that I met back in October of 2012 did not really have anything to do with me at first until just recently when we did VBS starting on June 16 together in recreation. We would throw a frisbee around and every time I or someone else would mess up she would look at me and smile like she was teasing me or just seeing if i thought what happened was funny. She calls me "chandelier" sometimes. Whenever both our eyes meet she smiles at me other than that she does not really talk to me she just smiles at me when our eyes meet. Just today when we were play capture the flag at our church towards the end... Me and her little brother Danny walked up to the back door where her and two other girls were and she smiled at me... Then after a while,I walked back inside and stood there. Then when I saw her friend wanted me to open the locked door, I opened it an Lexi tried to squirt a small water ballon in my face as soon as i opened the door and then she laughed a little bit. I have herd that she has a history of being shy. Could that be why she does not really talk to me? Could it be that she knows I like her and she is taking advantage of it? Or is she just giving little hints that she likes me. I haven't noticed her mess with any other guy but me. At least that is how it seems. I'm just not sure what to think about all this... It is just really confusing.. I would love a THOUGHTFUL answer to my question.