The guessing game is totally fun, I agree! I just giggle when people swear they have a dutch or dutch mix because it has a brindle coat, prick ears, and a pointy nose. I've seen three recently who think (swear) their dogs are apbt/dutch because of these traits.
That said... Malinois are unfortunately becoming exceedingly common and overbred in Mexico. However, the Malinois we're seeing from Mexico BYBs are very big dogs (read: huge) and very mellow (read: down right boring, sweet, no edge). It's possible she could have some Malinois in her long before the Dutch, imo, but I see a rat terrier/whippet/etc.
How's her edge? Nervous/distrusting? Aloof? Obsessive? Quick to startle? Overly aware? Easy to re-focus/maintain focus? Biddable?