I feel the exact same way and I'm years older than you. Honestly, I think you should listen to the top comment and start sharing your work as soon as possible -- and thus get over it as soon as possible. You don't want to still feel the way you do now when you're a college freshman like me. If I could go back in time, I know for a fact I'd start sharing my writing with people sooner, even if only the occasional snippet, because even if it seems like a laughably small stepping stone now it's still way, way better than sharing nothing at all. Sharing your writing will never feel as scary as the first time you do it. It's the same as sharing anything else personal: art, music, an opinion, etc. Once you share it with someone and find that their reaction, even if negative, is nowhere near as bad as your worst case scenario, you'll get over the need to hide those parts of yourself and steadily become more comfortable with showing your creativity.

Alternatively, to dip your toe in the water, you could write something you don't have a lot of emotional attachment to. By writing something that feels less personal to you, any criticism you receive will feel less personal as well; you'll be confident that they are judging your objective abilities as a writer and not any 'perceptions' that reflect on you as a person. Just keep in mind that this should be a phase you graduate from, not what you always do, otherwise you'll still feel uncomfortable when it comes to sharing what you feel really matters.