Is it normal that i feel much older than i actually i am?

It's normal. I felt that way growing up, too. I think most people do and sometimes, it's actually immaturity that can make someone feel like they're more mature than others their age. Sometimes people get the impression that they're more mature because of their interests, while emotionally they're the same maturity level as their biological age.
I don't know you or your circumstances, though. You very well could just be maturing faster. Some people do.

I remember when I was 13, I thought I knew absolutely everything about the world and that I was completely grown up. When I turned 21, I realized that I pretty much knew nothing when I was a teenager and still had a whole lot to learn. At 25, I still don't know what I'm doing half the time and just have to wing it. That's part of maturity- realizing you'll probably always be learning how to handle things in better ways.

As for dealing with immature people, that never goes away. There will always be some people who act like children their entire lives and that's okay. Just try to remember that everyone has advantages and deficits in certain areas when it comes to maturity and if it bothers you, then just ignore them. They'll come around and eventually, you'll probably "slow down" in maturing, so to speak, and get to the point where your peers have caught up to you.

It is normal.

I guess you feel that way maybe due to your upbringing. Some people, are babied and spoiled. So they grow up with the notion, That they'll always be taken care of. And that everyone, should treat them the same as their parents, did. I have a brother like that. He's in his 30's and my parents, are always bringing him food. And paying for him, even though he's has a pretty good job. So I guess your lucky to be so mature for your age.

I'm 25 n can b immature as fuck depending on my envorment but I can also turn that shit off with da quickness n Ima dude.I think females in general mature rather fast so I think its all good

Yes. I've had arthritis since I was 16, a bad arm since I was 12. The stress alone from that, mixed with surgeries, self esteem issues, glasses, hearing problems, etc.. always made and still makes me feel older than I am. Fatigue.. every day.. no matter what.. I feel like I'm 30 or so and I'm only 24.

I felt like a 78-year-old when I was six. Normal.

I'm the opposite. I feel 4-12 years younger than my actual age.