What did she mean by this?

Ok, so I like this girl but she's really confusing. She likes to flirt with me by touching my arms and chest. She also stands really close to me whenever she can. She teases me all the time by calling me loser, dork, and nerd. Sometimes when I do stuff she'll always call me lame. So recently my friend told her I like her and she was a little bit distant. Then she warmed back up to me like the next day. Since then she said stuff that got me mad and assuming I knew why I said "you don't have to worry about me liking you alright?" And she seemed a little taken back. Her attitude since then varies because some days she's really nice and others she is cold. Today I asked her if she'd like to go with me somewhere and she said "no thanks I have my cousins birthday later" and at first I said cool, but as I thought about it I tested back and said. "You'd tell if it was for any other reason right?" And she responded by saying maybe. So I don't know how to take that. We went out a while ago and we hit it off or so it seemed and I thought we were just friends then so never asked her again. Since then she still flirts with me and gets jealous of other girls when I talk to them or think they're attractive. So I don't know what to think.