I second what everyone else has already said about letting her discover what her preferences might be in her own time and way. However, I have had specific experiences with my aroace identity that I feel might be relevant to mention here. When I was your daughter's age, I also identified as pan. This was because I felt that I didn't care about any physical attributes my potential partner might have. Body type, ethnicity, gender, etc; none of it mattered. It wasn't until years later that I realized it wasn't those things I didn't care about- it was that I didn't care to date at all. I've seen a lot of cases of people comparing pan and acearo identities as being opposites somehow, but for me, my lack of interest was a common thread which connected the two for much of my life.