Welcome to my reality

Lately, I’ve been seeing this girl but the thing between each other is really strange. The thing that is not strange at all is the fact that is just 19 years-old, at least compared to other things.
We got along really well from the beginning. She is very independent woman or at least appears to be. We saw each other a few times although we haven’t gone out on a date since we met. It’s what happens when you are neighbours. One day, we were in her flat talking about nothing and in a moment that she is laughing I reach out and kiss her. She kisses me back and we make out for a while. There was conflict inside her because she mumbled a few times “what am I doing?”.
That evening she told me just before I went home that she was of relationships and that this had been a problem in the past for her. I told her that I thought we had potential for a good relationship but I was better to take things easy and see how things develop.
I’ve showed her a few times that I like her and that I want to spend more time with her but she is kind of distant. Well, here lies the problem. Her words and her actions are contradictory.
She says things like “I didn’t miss you” or “You just want me as a toy” or “I’m kind of busy so maybe we shouldn’t see each other tonight”.
BUT... one day I talked we her for 45 minutes before I reached out and kissed her and just after that she complained that I was taking too long. Every time I asked her to come by my flat she came although she had said that she wouldn’t come. Also, when I have her holding by the waist and she says she has to go to study, she doesn’t actually make any effort to leave.
She told me that sometimes she likes being mean but she says things that get me really confused.
My theory is that she is testing me to see if I can stand her and not take things personally. When will she stop testing me?