You don't say how long. However long it is, she doesn't want to commit, so that's that. Actually what do you mean by that? Do you mean she doesn't want to sleep with you? That is up to her. I'm female. At 19, I was in a 3-year-long relationship with the man who became my first husband. We did not sleep together/commit until I was 19. If you are after quick sex - forget it. she's not that sort of girl.
If it's not about sex, it's different in some ways - but if this girl does commit - she'll be with you for life. You may talk about your future as a couple and ask what she expects. That's about it. ADHD does not come into it.