If people need to tell you to speak more than they arent helping you feel comfortable around them. Be comfortable with your quietness, it doesn't mean you're boring. Maybe it just means that you haven't found people who share the kind of interests that make you feel excited and talk. The right kind of people often bring you outbox your shell. But at the same time there is nothing wrong with being quiet. It doesn't always have to be an uncomfortable silence. Just be the listening ear people need i suppose.