Uninterested in social relationships?

Is it normal for a teenage girl to be very uninterested in "hanging out" or "going to the movies/mall" and any other sort of social activity. I usually keep to myself, and i don't really like meeting new people. Some people are very insistent in getting to know me, even if we have nothing in common, or can't keep a conversation going for 2 minutes. It gets annoying having to feign interest in someone just because I feel as though they're just trying to be nice, so I should give them a chance. I just think problems might arise if I keep this up. Could this be a personality disorder? Any tips or any shared experiences? Thanks!