Why does she text me randomly but not keep the convo going?

A girl that I like she lives several states away now. I knew her before but hadn't seen her in years. We met up and hit it off but she was moving. Well in the few weeks before she moved we hungout as much as we could kissed every time we were around each other, held hands and had a great time. We never addressed what we were before she left. After her move we talked almost everyday for the next two weeks. Then she went awol for a week and now we are talking again after she called to apologize for being rude to me. So we talked for about an hour and half the other night then the next day she texted me about music she was listening to. Then last night we had two text conversations. The first I started by telling her a band she loves would be on a TV special. We then texted for about 30 min until the convo kinda fizzled. Then an hour later she texted me when the band special was on and we texted for about an hour, then when it started to go lame I stopped responding. The conversations are pretty light and we joke around. Its just hard to gauge things in text. Then tonight she text me to listen to a band. The other day she told me about a song and I told her it was a slow dance song. She agreed. Then today when she texted me about this new song she said "slow dance song" then gave the song name. I responded saying "great, now I need a dance partner" thinking it was a good flirty text but she didn't really address that when she responded, just kept talking about the band. Then we texted for about 20 min about songs and bands to listen to. Then she seemed to lose interest. So I guess my confusion is why does she text me random things but then seems to become board of the conversation. And is it that big of a deal that she gets board? I like the fact that she reaches out to me but wish the conversations were better. So why does she does she text me? I need to know if she likes me more than a friend but I'm unsure of how to do that gracefully. I know she liked me before her move and she's kept contact but girls can be weird.

Some other background is that I have always found her hard to read on the phone. Before she moved whenever we'd have great talks on the phone but just good conversation, nothing that said "wow she likes me" which always made me nervous about how she felt. But then when we'd meet up it was always great, she was affectionate and we clicked. So even when I had facts that she liked me I never got good reads from phone talks. So it makes it hard to know what she's feeling since its the same feel.