Is it normal to have a sex buddy? and not a girlfriend?

Theres this girl, we have been best friends since elementary school. We did everything together, but when we turned 14 i started touching her and she started touching me.. and then it led to sex, now we're both very attractive people but we both havnt been in a relationship since we were 14 we are now 20 and all we do is hookup with eachother, i dont know if i want to settle down with someone else just yet but something needs to change.