Yep, Q is Queer (also sometimes Questioning). It’s kind of a fuzzy category to define from the outside, but covers people who don’t consider themselves to fall within any of the other categories.

Non binary and other gender nonconforming folks will often identify as queer. So may people who challenge cis- or hetero-normativity, monamory, and other social norms around gender and sexuality (look into “Queer Theory”).