Is it normal that as highschool ends, many of my friendships are too?

I guess you could say I'm a loner in a sense. I like solitary activities like playing guitar and reading but that being said, I have never been alone unless I wanted to be. I've never really been "popular" but I've always had friends and girls seemed to like me at least as far as I could tell.

Everything for me is changing right now however and I'm a little concerned. I'm half way through grade 12 and my relationships with my friends has dwindled down to mainly just talking and hanging out at school. In some ways it is my fault. I don't call them every weekend to hangout like I used to as I've been focusing on school this year. What troubles me though is that they haven't really ever made an effort to call me either since we started to drift apart. I know that they're just my friends and that I'm not dating them or anything but we had some fun times throughout high school and to be honest it hurts me that they just don't seem to care. When we did hang out it was mostly me calling them but they always seemed excited when I called and we always had fun. Since I've started focusing on school I haven't called them as much because they're bad influences to be honest, but I always thought they would therefore make the effort themselves and they haven't. I know it's a stupid thing to be troubled over but it makes me feel like I was always just a friend of convenience for them in the sense that if I called when they were bored we would hang out, but otherwise they didn't really care for me. I can still call them now and hangout most of the time if I want to but it's just not the same anymore because now I know that they'd never do the same with me. Even when we did hangout all we ever did was drink and get high with liquor and weed that was usually provided by me.

It bothers me because as I've been focusing on improving my grades, I've met a lot of new people that share my ambition and the desire go to university. I like these new friends of mine much better than my old friends but it seems to me like all these new people I talk to now already have friends of their own. They already have a life with things to do and people to see. I also feel like they assume I do too when I really don't. I have my old friends but I can't relate to them because of our differences in priorities and as I said above; I feel like they don't really care about me that much. Even though I don't really hang out with these new friends of mine a ton outside of school, they still treat me better than my old friends. When I walk into the classroom and my new friends see me, their faces light up and they look genuinely happy to see me. That's something I never got with my old friends. With my old friends I always felt like I was intruding on a conversation. I'm starting to wonder if they were ever my friends at all. I would like to get closer with my new friends but as I said, they have lives of their own and they assume I do too. I know if I asked to tag along, that they would definitely say yes but then I would be killing the illusion that I'm hiding behind right now; which is that I'm not nearly as sociable or interesting as I appear to be. I give off the impression that I have a lot of friends and I try to be confident because I find that's what people are attracted to but I'm now starting to wonder if it's all just an act. I feel confident. I feel cool but I don't have the friends to back that up like people often assume I do.

I just feel like I messed up throughout high school. I feel like I wasted my time with people that didn't really care about me and now in grade 12, everyone already has their groups of friends and they don't need anyone else. I read a facebook post yesterday where a guy was thanking his friends for throwing him a surprise party for his 18th birthday. It made me so sad because my 18th birthday is coming up and I know that if I don't make an effort to make plans, that I could sit at home my whole birthday and not a single one of my friends would even bother calling me.

I know I sound really messed up but I'm not really depressed at all. Obviously loneliness can get to me sometimes as it can with anyone but other than that I'm quite happy. I said I've been focusing on school and it's payed off more than I ever thought it would. Currently my average is well into the 90's and I just got early acceptance into the best business school in the country. I'm also taking the required courses for med school and I'm very seriously considering becoming a doctor. It's either that or getting my MBA. I have a lot to look forwards to in life but there's a reason I bring this stuff up and that reason is that my friends have nothing to look forwards to. Their grades are just good enough to pass and they don't really care about their futures and yet they are in a better position than me right now. They have other friends that care about them as far as I can tell and they seem generally happy. I'm happy but empty at the moment. I'm putting all my energy into the future. I'm happy because my future looks good and so I disregard whats going on in my social life right now. I like to think that when I get to university that everything will work itself out. That I'll meet new friends and that nothing from high school will matter anymore. That I'll feel like a part of a group. I'd like to think that, but more and more I wonder if there's something wrong with me. I wonder if I push people away. I wonder if my situation is not just going to fix itself and that it's something I'm doing wrong. I wonder if I'm the problem. I hate these thoughts and I shut them out because high schools almost over but the thoughts aren't just going to go away. What do you think? Is there something wrong with me?

I'd also like to apologize for the ridiculously long post but I had a lot to say and I've been holding this in for a long time. Please help me. I really need some advice.