How can I tell if she is just being friendly with me or is it more than that?

She and I barely know each other. But she has become very friendly with me one day randomly. She started giving me a shy smile and wave. Now she is giving me a big smile and wave from across the cafe. It has just progressed from there to her talking to me and I feel happy when we talk. She has initiated a lot of contact with me in person. There has been questions asked like " what time do you start work?," where i grew up?" " what I'm doing this afternoon?"
How can I tell if she is just being friendly with me or is it more than that?
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