Open Question: Why might she be doing this?

So I have this female friend (she says she is straight).
I am also female and out as being gay.
Basically she play fights with me all the time like slapping, punching, kicking, pinching (just messing around though), she gets defensive if i start talking to someone new, she also touches my legs and hands and attempts to tickle me every now and again, she sings and holds out her hand as if to say hold it and stuff. We spend quite a bit of time together at school and sometimes skype outside of school, we are often seen laughing at something that the other one has said. thing is we aren’t that close. My other friends say that it seems as if we are flirting with one another although when she goes to touch me i shy away and i refuse to hold her hand and stuff. I used to have feelings for her in the past and my friend says that me and her give each other looks that are a bit different to normal friends and stuff and that the stuff she does with the play fighting im the main one she does it with now and its always happening.

I’m just not sure what she is doing or what it might mean, any ideas?

Thanks guys!

Open Question: Why might she be doing this?