One thing about being older is, if you were lucky enough to be in school both as a young person as well as, well, now, you know about both ends of the experience. And here I am, old enough to talk about "when I was your age." (You hate it now, but in a few years, you will love it....)
When I was your age, I was also bright and enthusiastic, and a lot of what I had to offer was discounted because I was young. I too was often right.
I recently completed nursing school. I am not young anymore, but many of my classmates were young, some as young as you. I enjoyed them all, and respected them, and in truth, I usually forgot that there was an age difference. (One nice thing about getting to this place is that you feel about the same as you did at 25 or 30--it's also one of the bad things, but that's a story for another time.
Guess what. I felt disrespected by my younger classmates at times too. I felt they discounted my opinion and ability because I was older than they were. And they might have, and that's okay, because it was their choice.
One hard lesson I learned (before nursing school) was that what other people think of me is none of my darned business!
My advice to you is this: focus on enjoying your classmates and preparing for nursing. The rest of it will fall into place. Until they actively push you away and say something like we don't want to be around you because you are too young (or whatever) you can assume you are still welcome among them. Your reaction to "how it might seem" (my quotes...) is your own. If you ignore it, you can get the most out of both nursing school and your friends from generation whatever (what the heck are we in my generation anyway?).
A little off topic: don't let someone else's questioning of what you know to be so, affect your self confidence. You sound very bright and very sensitive. You can make that work for you and continue to develop into a super nurse and sterling human being.
Sounds like you are well on your way. Thanks for your post, hon! Very nice job.