i've said it before and i'll say it again, slaves and conquered people are two different things!
and she does NOT flat out say she is mandalorian, she tells you she is a slave. being a slave does not automatically make her a mandalorian.
she says "as much as any slave becomes a mandalorian"
sure, in some societies slaves could earn their freedom, but there are no sources in the game to suggest that mandalorians do the same thing. so she could be implying that she became a mandalorian, or that she (like other slaves) would stay exactly that, a slave, and could never become a member of mandalorian society
yes mandalorians do recruit people, but slaves aren't exactly recruits are they?
i'm not saying flat out that she isn't mandalorian, i'm saying that it is never truly revealed, and that saying that she is mandalorian is an unverifiable assumption