I really like the message in your hashtag, and I like this campaign, but I wish it didn’t try to focus so exclusively on gender, mostly because the billboard issue that motivated it is not exclusively a gender-based conundrum. The other examples you gave are definitely gender-based discrimination/harassment, and it’s clear that there’s a lot of bias/unfairness that women still have to deal with in the tech world (also, that latter guy is basically a “bad” guy — messaging a prospective student for sex shows pretty poor comprehension of any reasonable ethical standard, and it shouldn’t be so easily dismissed).
But that said, I don’t think that gender is the main reason that people commented on your ad. When people say “you don’t look like an engineer”, they’re saying it because you don’t fit engineering stereotypes, and for you, it’s because you’re quite pretty and evidently fashionable (and female —I doubt those qualities would prevent males from “looking like engineers” to the same amount of people, so clearly the reasoning isn’t mutually exclusive).
My point is that the issue you’re seeing isn’t that people don’t believe girls can be engineers; rather, people still don’t think that there’s much variety among engineers — and that’s diluting the profession. Most of this article even says that. Efforts to fight gender discrimination are necessary and helpful, and if that’s all you do, it’ll still be a wonderful legacy for your efforts; I just think that your campaign could be more powerful if you really embraced the hashtag and focused on the idea that anyone can strive to be an engineer.
Anyway, this comment got long. It’s admirable that you’ve been able to inspire others and get people talking. Hopefully you’ll continue to have the impact you’re looking for.