I'm a very young millennial (born '96) and do not know anyone my age interested in permaculture. I joined a local permaculture group composed of some of the loveliest middle-aged and older men and women, though, and I do feel very welcome amongst older people. However, I do long for companionship and shared interests from people my age.
I believe my interest in permaculture was fostered because I was incredibly lucky to be born and raised on a sustainable farm. I kick myself for thinking it was so uncool as a teen, and moving to a hip city at age 17 to go to college. I'm happy with my engineering degree, but I know for a fact that I do not belong in the corporate world or in a city, I would be much happier doing freelance work. Most of my friends my age disagree, and are perfectly happy/strive to work in large corporate environments with hip cultures or for large research/academic institutions, and prefer to live in a large city. We're lucky to be part of the generation that is more environmentally conscious, but most of them have no interest in living on a farm.
I'm currently working in a corporate engineering job and living in a large US city, the millennial dream, so I'm unfortunately nowhere near as successful as you! But, I do have a plan that I'm working on putting into action. I designed some off-grid and efficiency solutions in undergrad, and had the time of my life doing so. I'd love to do that professionally, I'm just figuring out how. As for permaculture itself...there seems to be nothing more meaningful than hard work and the community/relationships that come with it. That is what I am after.