How are the opinions of others imposing on your freedom? In my experience, if you feel restricted by the kind of people you're around, you need to make more of an effort to surround yourself with people who understand you and have things in common with you. Speaking as a moderately antisocial person, I know I'm not going to enjoy the company of or feel validated by the vast majority of people, but that just makes the few people I get close to all the more special. And it sounds like you need to be careful about generalising everyone your age because of the way you perceive most people your age to act and think, even though you clearly see yourself as an exception, and therefore exceptions are possible. For one example from your list, not every woman over 25 wants to get married, either immediately or ever. From my experience, putting too much stock in generalisations, however statistical they are, can lead down a dangerous road of myopia, resentment, self-pity and even persecution complex. So try to see people as individuals and put yourself in situations where you'll meet like-minded folk, that's my advice.
On the general topic, I think that not just reaching adulthood but ageing in general facilitates new freedoms as we're able to gain deeper understandings of the world through experience. As the adage goes, "the truth will set you free", and as we age we get more opportunities to hone our tools of rational analysis, develop and test theories about the world, and make discoveries about ourselves and others. Growing this way increases our potential for meaningful agency. The more we're aware of, the more ways we can use this awareness. As we gain responsibility for our own lives there are some constraints on what we can and can't do, but as adults, we can make much more significant decisions about the kind of life we live. The most restrictive forces I can think of are problems with the way the world's run, say, the way capitalism serves the most powerful people in society and relies on the existence of a comparatively powerless underclass. The opinions of my social peers don't have any bearing on my freedom compared to forces like that.
Your post seems to reduce "freedom" to the specific behaviours we can engage in without being judged by others. But to me, if freedom was just the general approval of the ways I express myself in the same terms it's granted to kids -- with the condescending presumption that I'll grow out of it, etc. -- I wouldn't value it. Real freedom is complex and challenging. In a world where free agency is constantly interfered with by crap like direct misinformation and systematic power imbalances, it seems a little petty to call slightly limiting social standards a lack of freedom. Sure, it'd be nice if in general people were more open-minded, but like I said, it's the exceptional individuals who count. If you want the world to be less hostile to the way you express yourself, your focus should be on how you can contribute to a more open-minded culture by judging others as individuals and not giving two bits about the normative standards of the nebulous society-at-large.