Why it's so hard to make friends?

I'm (18.5M), and I just can't seem to make friends whether in college, outside, or anywhere else. It always feels awkward and weird whenever I try to talk to someone, regardless of their age. Even when I do try, I struggle to form sentences and keep the conversation going. I rarely find people with whom I share common ground, and even when I do, I'm afraid to talk to them and I don't know why. Since childhood, I've barely had two or three people in school who could even be considered friends (and even then, they mostly just know me for some specific reason). There's no one who truly knows me. Now that I'm in college and have completed my first year, I still haven't made any friends. I really want to, but something inside me keeps holding me back. Thanks.