Why do I feel like this?

Even though you don't think so, I think it's a crush. You aren't emotionally attached to her yet, but you're thinking about her a lot. If you decided to pursue a girl-girl relationship with her, I think you'd find that your emotions will sort themselves out. Your emotions will tell you that you were just crushing & wanted her to crush right back on you. You should call her up & ask her to do something with you. Even if you don't pursue a romantic relationship, still hang out with her until your feelings pass. Try looking for someone new.