Are you an only child? I am and I find that I actually want alone time frequently. I have always been like this. I have always had friends and enjoy going out w/ them (especially when I was younger).
DH is somewhat that way as well. He had 2 brothers, but there was a big age difference between him and the younger one and the older one left home right after he graduated hs. He then lived by himself for quite a few years.
I don't think you are messed up at all. I think that being able to be comfortable by yourself is a gift. Some people can't handle it.