I don't know you personally - but my friend's are the exact same, and I just laugh it off. They mostly have no idea what they're doing with their lives and yet have no qualms criticising other's plans. When someone's criticism isn't at all constructive, they most like have a motive for criticising that isn't to help you. Many of my friends have greater flaws to their personality than awkwardness, and underneath it all are less self-secure than me. Some people will always readily tell you what you can't do, what's impossible - I derive motivation from that, with the desire to prove them wrong.