Why don't I have any friends?

I had so many friends in primary school (which is elementary for all you Americans :P), probably because it was a very small school and we all grew up together. Most of them went to the same high school, and I went to a different one. I still kept in contact with my best friends, but I only saw them a few times a year, and at school I was friendless. I sat with people but they would often just get up and walk away without me. It was like that for 2 years, and I finally had enough and moved schools. Now I go to the same school as my best friends, and I have a lot of acquaintances. I sit with a big group of people with some of my best friends from primary, but they NEVER invite me anywhere. They always go out together, but always forget about me. I have another group of friends from primary, and I sit with them too, but it seems like they're always angry at me. They act like they're really annoyed at me and never invite me anywhere either. And I always try to make plans with them, but they're always "too busy." I had some other good friends, but they went to different schools and we just grew apart. I'm friendly with pretty much everyone, but people never want me in their groups for projects and things, the teacher has to put me into a group. I can't seem to relate to people my age, like I have entirely different interests in music and style and things like that. Also, when everyone's complaining about learning something, I'm the kid who says it's for our own benefit, and everyone thinks I'm lame for that. Is this why I don't have friends? I always try to be really friendly and funny, and I don't think I'm shy... What do I do? It's pathetic that I have no social life, even though I don't really mind, it's just at school... Is it okay if I have no friends in high school? I only have 2 more years to go and then I'll probably never see any of these people again.