Being an introvert

I've recently been toying with the idea that as I near the big 3-0 I'm becoming much more introverted. A friend of mine was the one to point this out to me after I'd been explaining how a day of socialising usually meant I required even more time to myself to feel sane again. He suggested I was either becoming more introverted as I grew older, or perhaps always had been but had been suppressing it. 


An introvert is defined as 'a person characterized by concern primarily with his or her own thoughts and feelings' but is often misconstrued as meaning shy. The definition makes it sound like I must be narcissistic but that's not the case. It simply means that I enjoy my own company, exploring my own thoughts and feelings and spending time by myself. 


To some extent I've always been like this. I was an only child until the age of 15 but even then my brother never lived with me, so I've always been very good at occupying myself. The change I have noticed, is that in the past I used to love going out socialising as long as I had some time to myself. I'm finding that I am increasingly needing more and more time to myself, and if I don't get it I feel really awful mentally. 


I always used to be the kind of person that had plans nearly every day of the week, but now I find this completely overwhelming. If I can't see breaks in my diary for "me time" I completely freak out and feel almost suffocated. It means the plans I have feel like chores and just something I have to do in order to get to the me time. 


I was living like this for a while and it was just ridiculous. What was the point? I was no longer enjoying the company of my friends so why was I bothering? Once I accepted the fact that maybe I had become more introverted, and saw time for me as a necessity my mind started feeling much more calm and sane. It's hard to explain to people sometimes that you can't see them, especially if they see it as you "doing nothing" but most of my close friends are completely respectful of this and simply cherish our time together even if it is less than in the past. It is hard. It's a balancing act, but now I've come to accept this change hopefully life will be a lot more enjoyable. 


Are you introverted? What have your experiences been? I'd love to hear them.