Beginning of November girl I knew asked for my number. Since then I have received many signals that she's into me. I never really got things rolling and over Christmas she told me she didn't like me after I told her I liked her.
Now she goes through periods where she will text me like crazy and periods where I might text her and get no reply. Some of her texts to me are sexual and I play along. In class she always initiates conversation and little things like drawing on me or commenting on my strength etc. I fall back into liking her after I had successfully found a way to ignore her out of my life.
So I realize how I came off way too needy before with her and I'm more cocky and funny towards her, but whenever she starts acting like she's into me and I play along and start to like her, she backs off. Am I wasting my time with an attention whore or is there something else behind this?

If you had her number since NOVEMBER, what the hell have you been doing all this time? You get a girl's number in order to ASK HER OUT to one on one situations in order to gain her trust and raise her sexual feelings in order to fuck her brains out.

You don't get a chick's number in order to text her back and forth for six months. This is like buying a fishing rod in order to sit on your living room couch staring at it all day long. Even a fishing rod would be pissed with this predicament.