We think faith is about us, but it’s not about us at all. “I have X amount of faith.” Faith isn’t about the *subject* of faith, but about the *object* of the faith—faith is about the trustworthiness of the person in whom we are putting our trust.
This is why Jesus says that even the smallest amount of faith can move mountains, and why the disciples were unable to heal the afflicted boy who was brought to them.