If I don't want a girlfriend, why does everyone assume that there's something wrong with me?

I'm 19. Never had a girlfriend. Never wanted one. Never even been kissed. This doesn't bother me at all. It seems to bother other people. It bothers my family. It bothers my psychiatrist. All I do is work & go to school. I'm in college. You would think by working & getting an education that people wouldn't bother you, but apparently they do. I don't know if I'll ever get a girlfriend. Sometimes I see myself getting married & having children. Sometimes I don't. That's too far ahead in the future for me. I'm not an animal. I don't let instinct or hormones control my life. I know society tries to get everyone to lose their virginity by age 12, but I don't go by what society tells me to do. Why can't people just get off my case?