Your introverted nature doesn't mean you can't handle presentations, it just means you might prefer to handle them in small doses and with a bit more time to prepare. You might worry that your presenting style isn't as big as some of your more extroverted colleagues, but have no fear, your natural, candid style of delivery makes you accessible to the people you are presenting to, and it also keeps the focus on the content of the presentation. Just make sure to take care of yourself afterwards, as presentations can be draining even for the most extroverted of workers.