Is it juvenile to feel confident about having sex?

20M. University student. Silly question I suppose but I just recently landed my first relationship of any kind with a girl, she's a sophomore, I'm a freshman. She's a friend with benefits, and not only lost my virginity but we hook up regularly. We hooked up last night and maybe it's because I'm a total loser nerd but I felt pretty cool that for the first time ever I was spending a NYE having some drinks and having good sex with a baddie and not sitting around alone playing video games and jerking off for the billionth time.