Thank you <3 (I didn't make the layout/site though! My sister who is a fancy pants web developer sent me a link, yelling at me to go make a portfolio on it, so I did)
I don't think there's really an age limit to making a portfolio for yourself - in fact, I think it's pretty good that you're thinking about it now!
I'm waaaaay self conscious, and I'd been meaning to gather some of my stuff together for a long time, but the only reason I actually kicked myself into doing it is because I'm finishing uni soon, and I'd like to maybe get a job that isn't in retail (n-not that working in retail is a bad thing, it's just I would prefer to not to have to know how to work a cash register because that scares me, also I'm a lazy jerk whose never had a job ever and art is the only thing i know how to do semi-competently???)
But yeah, you should at least start gathering your own works that you're most proud of and put them somewhere where other people can see them, separate from sketches etc (unless you're going for a concept-arty vibe), because even if you're not able to take on commissions or larger jobs at the moment, at least people will see your work. And obviously as you grow as an artist and feel more comfortable with your work, you can swap out older stuff/stuff you don't like as much any more, because that's totally what I plan on doing.
TL;DR I don't think age is a big deal? I mean if you feel confident enough about yourself/your art then people will generally respond in a good way, and there's no harm in thinking ahead and getting your stuff out there.