Maharaja: IT's perfectly normal to be single at 19, at least in the United States. "Normal" is in the eye of the beholder. I was single until I was 25. There's nothing wrong with that.
I dont' know why anyone would refuse to date someone who has been in a relationship before. Of course, that's your choice. By the time you're 19, you're not going to find many people who haven't been in relationships. Having someone who has some experience can actually be an asset in relationships. Of course, you may PREFER someone who hasn't. That's no one's decision except yours.
Who we date is ultimately a matter of preference. There's no absolute right or wrong answers, as long as everyone involved is a consenting adult.