> The (consistent) impression I was given was that if you didn’t try to constantly talk about being a girl/woman the majority of people just didn’t really care.

Not mentioning your gender when you have a gender-neutral username means people “don’t really care” you’re a woman because they just assume you’re a man. But often the mere mention of the fact you’re a woman, however relevant to the discussion, is viewed as “constantly talking about” your gender.