Yes and no (I feel like I answer every question here with that, ha).
In a way, I actually feel much older than I am. Because I had to battle a lot of things -- both internally and externally -- to just be myself, I occasionally feel more mature and otherwise more advanced than some of my peers. I know myself intimately, which is not something everyone achieves, and I endured a kind of trial by fire to get where I am.
On the other hand, I certainly feel like I missed out on some things while growing up the first time around. I don't feel super young, but more like, say, a college freshman or sophomore. I want to explore and travel and experience so many different things, and it's kind of overwhelming (but in a good way). I have a seemingly unquenchable thirst for life that I just didn't before.
Of course, if you posed this question to a cisgender twenty-something (or even a thirty-something), you'd probably get a similar answer. A lot of people struggle to come to grips with adulthood or at least to perceive themselves as not a kid anymore. We all have different reasons for it, but overall, this feeling might just be part of the human condition.